Month: March 2024

Here’s the hard truth about email marketing: your beautifully crafted campaign means absolutely nothing if it lands in the spam folder. You can have the perfect subject line, gorgeous design, and compelling offer, but none of it matters if your subscribers never see it.

But here’s what matters: email deliverability isn’t magic—it’s a system you can control. Once you understand the technical and strategic elements that mailbox providers use to separate legitimate emails from spam, you can consistently land in the inbox instead of getting filtered out.

This guide breaks down how email deliverability actually works, what you can control, and the steps you need to take to consistently land in the inbox.

What Is Email Deliverability?

Email deliverability is the measure of how successfully your emails reach subscribers’ inboxes rather than being filtered into spam, promotions, or getting blocked entirely. It’s how you do successful email marketing—without it, even your best campaigns may go unseen.

Email Deliverability vs. Email Delivery

Here’s where it gets tricky—delivery and deliverability aren’t the same thing:

• Delivery means your email reached the recipient’s mail server. 
• Deliverability means it reached their inbox.

Email delivery is binary: your email either got accepted by the receiving server or it didn’t. Email deliverability is about whether your email reaches the inbox, gets filtered to spam or promotions, or bounces back before delivery.

Why Email Deliverability Matters

Poor deliverability wastes your marketing budget and damages your email sender reputation, making future campaigns even harder to deliver.

Imagine you’ve spent hours perfecting an email campaign: polished subject line, tailored message, smart contacts segmentation, compelling email CTA. But all that effort depends on one critical factor—whether your email actually reaches inboxes. An undelivered email is like a billboard in the desert: it might be a masterpiece, but if no one sees it, you get zero engagement and zero results.

Here’s the critical distinction: you can have 100% delivery (every email accepted by recipient servers) but terrible deliverability if all those emails land in spam. That’s why deliverability is what actually matters for campaign success.

When an email gets stuck in spam or bounces back, you get zero engagement and zero conversions. But the damage doesn’t stop there. Email service providers track how recipients interact with your emails, and each ignored, deleted, or spam-marked message signals that your content isn’t wanted. Over time, providers learn to automatically filter your future emails based on this pattern.

Without solid deliverability, you’re essentially wasting your marketing budget on messages nobody will ever see.

What Factors Affect Your Email Deliverability?

The good news about email deliverability is that most of it is within your control. While you can’t force mailbox providers to deliver your emails, you can influence their decision by managing these key factors:

• Sender Reputation
• Email Infrastructure
• Email Authentication
• Email List Quality
• Recipient Engagement
• Email Content

We’ll dive deep into each of these factors throughout this guide and show you exactly how to optimize them.

Sender Reputation

Your sender reputation is a score mailbox providers assign based on your sending behavior. Low reputation means spam folder placement, while high reputation means inbox delivery.

Mailbox providers track everything: email bounce rates, spam complaints, email engagement levels, sending patterns, and authentication setup. This data determines whether your emails deserve inbox placement.

What is Sender Score?

Sender Score is a specific metric (ranging from 0-100) that indicates how good or bad your sender reputation is. It’s calculated by tracking your IP address’s email sending behavior over time. A score above 80 is considered good, while anything below 70 can hurt your deliverability. 

Your reputation has two key components: IP reputation and domain reputation. Both matter, but they work differently and require different management strategies, so let’s break it down.

IP Reputation

IP reputation tracks the behavior of your sending server’s IP address.

If you’re on a shared IP, you share reputation with other senders using that IP. On a dedicated IP, the reputation is yours alone to build or destroy. Businesses typically use a dedicated IP when they send high volumes of email or want full control over their deliverability, but that also means you must build a positive reputation from scratch. We’ll explain the differences between shared and dedicated IPs in more detail later in this guide.

When your IP is brand new, you have to build trust gradually—which is why new IP addresses need a slow ramp-up in sending volume over 4–6 weeks. Mailbox providers have no data about you yet, so sending thousands of emails immediately matches classic spammer patterns and triggers blacklisting or heavy filtering.

IP Warming Schedule:

• Week 1: Send to your most engaged subscribers only, low volume
• Week 2-3: Gradually increase volume by 50-100% weekly
• Week 4-6: Continue scaling until you reach target volume

Monitor email marketing metrics closely and slow down if you see deliverability drops

Common causes of blacklisting:

• High bounce rates, especially hard bounces (we’ll cover bounces in detail in the Email List Quality section)
• Excessive spam complaints
• Hitting spam traps
• Sending to purchased or scraped email lists
• Sudden unexplained volume spikes

Now, with all this said, most businesses don’t need their own dedicated IP because their email platform handles IP reputation on their behalf. So one of the main goals of email service providers is to maintain a good sender reputation for their servers and IP addresses to guarantee high email deliverability for their clients. 

Reputable email service providers do this by monitoring networks continuously to keep IP addresses clear of activities that could lead to blacklisting. They manage pools of multiple sending IP addresses, building reputation carefully for each one. If a blacklisting event occurs, the problematic IP is removed and replaced with a clean one—without affecting sender scores or raising red flags with mailbox providers.

This proactive approach to managing mail servers and keeping IP addresses clear of spam-related behavior increases the likelihood that mailbox providers will accept your emails, helping your messages reach subscribers’ inboxes and supporting your campaign success.

At SiteGround, system administrators monitor the network 24/7 using this shared IP management approach. Multiple sending IP addresses are managed in a pool, with reputation carefully built and maintained for each one. If any IP faces issues, it’s immediately rotated out for a clean one—all happening behind the scenes without disrupting your campaigns.

Domain Reputation

Domain reputation tracks the behavior of your sending domain and has become increasingly important as authentication has improved.

Unlike IP reputation, domain reputation follows your sending domain regardless of which IP or email service provider you use. Even if you switch providers or IPs, your domain reputation travels with you—making it both more stable and harder to escape if damaged.

What Affects Domain Reputation:

• Authentication setup: Proper SPF, DKIM, and DMARC configuration
• Sending history: How long your domain has been sending emails
• Engagement patterns: How recipients interact with emails from your domain
• Spam complaints: Reports tied to your domain across all IPs
• Consistency: Stable sending patterns over time

Why domain reputation matters even more now:

Mailbox providers increasingly weight domain reputation over IP reputation because:

• Authentication protocols tie emails to domains, not just IPs
• Spammers frequently switch IPs but can’t easily switch established domains
• Domain reputation provides a longer-term view of sender trustworthiness

The key difference between IP reputation and domain reputation is that a bad IP reputation can be fixed by switching IPs (which your email service provider can manage). A bad domain reputation is harder to recover from because it’s tied to your business identity. This is why maintaining proper authentication, list hygiene, and engagement is critical.

Email Authentication

Authentication protocols prove your emails are legitimately from your domain and haven’t been tampered with. Without them, mailbox providers will filter or reject your emails.

Mailbox providers need to verify you’re not a spammer or phisher—it’s how they protect users from fraud, prevent unauthorized access to information, and maintain service integrity. They check authentication records in your DNS, which act as your digital credentials confirming your identity and sending authorization.

Quick Authentication Overview

Let’s break down the four main authentication protocols, what each one does, and why you need them. We’ll dive into the details of how each works right after this.

Protocol	What It Does	Why You Need It
SPF	Lists which servers can send from your domain	Prevents email spoofing
DKIM	Adds a digital signature to verify authenticity	Proves emails weren’t tampered with
DMARC	Combines SPF + DKIM and sets policy rules	Tells providers what to do with failed emails
TLS	Encrypts the connection between mail servers	Protects content during transmission

Next, let’s break down exactly how each protocol works.

SPF (Sender Policy Framework)

SPF is like a guest list for your domain—it tells receiving servers which mail servers are allowed to send emails on your behalf.

When someone receives an email claiming to be from your domain, their server checks your SPF record (stored in your DNS settings) to see if the sending server is on your approved list. If it’s not listed, the email gets rejected or sent to spam.

This prevents spammers from pretending to send emails from your domain. However, SPF alone isn’t enough anymore—it’s the oldest authentication protocol and mailbox providers now require additional layers of verification. That’s where DKIM comes in.

DKIM (DomainKeys Identified Mail)

DKIM adds a digital signature to your emails that proves they came from your domain and weren’t altered in transit.

DKIM works like a tamper-proof seal on your emails. You create two digital keys: a public key that goes in your DNS records where anyone can see it, and a private key that stays with your email server to “sign” outgoing messages.

When you send an email, DKIM stamps it with an encrypted signature (a unique digital code that can’t be forged). Receiving servers check that signature against your public key to confirm everything matches. If it does, they know the email is authentic and unmodified.

This digital signature is a powerful trust signal that significantly improves inbox placement rates.

DMARC (Domain-Based Message Authentication)

DMARC combines SPF and DKIM, then tells receiving servers what to do with emails that fail authentication checks.

DMARC creates a policy layer on top of SPF and DKIM. You specify whether failing emails should be quarantined (sent to spam), rejected entirely, or delivered with a warning. You also get reports showing who’s sending emails from your domain and whether they’re passing authentication.

Think of DMARC as the security guard who knows exactly how to handle uninvited guests based on your specific instructions.

TLS Encryption

TLS (Transport Layer Security) encrypts the connection between sending and receiving mail servers, protecting email content from interception.

When your mail server connects to a recipient’s server, TLS creates an encrypted tunnel for your email to travel through. This prevents anyone from reading or tampering with your message during transmission.

While TLS doesn’t directly authenticate your domain, mailbox providers increasingly favor senders who use encryption. It’s a trust signal that you take email security seriously.

Setting Up Authentication at SiteGround

To help you in this process and make sure your sender reputation and email deliverability do not get hurt we do two things:

Every new client who signs up for our email marketing service and whose DNS zone is managed by SiteGround gets all these records automatically set.

And for everyone using the service with or without your DNS being managed by SiteGround, we block the sending of email campaigns from domains that are missing any or all of these records, saving you from hurting your domain and sender reputation until you set them up.

Why Authentication Matters: Gmail & Yahoo Requirements

In February 2024, Gmail and Yahoo made authentication mandatory for bulk senders (5,000+ emails daily). Without proper SPF, DKIM, and DMARC setup, your emails won’t reach Gmail or Yahoo inboxes—regardless of content quality.

SiteGround handles the technical setup automatically for managed DNS users. However, you’re responsible for maintaining list quality and keeping spam complaint rates below 0.3%. Learn more about Gmail and Yahoo sender requirements.

Bottom line: All four of these protocols work together to prove you’re a legitimate sender. Set them up once, and they run automatically in the background.

Email infrastructure

Email infrastructure is the technical foundation that sends your emails—including mail servers, IP addresses, DNS configurations, and network systems.

It determines whether your emails can be sent reliably and how mailbox providers perceive your sending servers.

Server failures, downtime, or poorly managed IP addresses will kill your deliverability before content or design ever comes into play. This is why partnering with an experienced email service provider—one that handles high volumes daily and has backup systems in place—is so important.

Did you know that campaigns sent through SiteGround Email Marketing achieved a 98.80% delivery rate and 36% average open rate? Those numbers don’t happen by accident—they’re the result of infrastructure designed specifically for reliability and inbox placement. Here’s how SiteGround makes that happen:

SiteGround’s Unmatched Infrastructure Redundancy

SiteGround offers both email marketing and email hosting services. Over 20 years, this has built expertise in managing email servers from both perspectives—the sender side (what email marketing platforms do) and the recipient side (what hosting companies and email service providers do).

SiteGround processes 6+ million outgoing emails daily while receiving millions more through hosting services. This dual perspective has led to infrastructure customizations and software solutions that increase deliverability for outgoing emails and reduce spam on both sides. This expertise has made SiteGround a leader in email deliverability.

Multiple Redundant Infrastructures

SiteGround maintains several fully functional email infrastructures across different data centers. If one system hits technical issues, another takes over within minutes with zero disruption to your campaigns. This eliminates single points of failure from power outages, connectivity issues, or data center problems.

What does this mean for you? No waiting around for servers to come back online, no rescheduling sends, no wondering why the promotional email never went out.

Managed IP Pool with 24/7 Monitoring

SiteGround’s team monitors IP address pools around the clock, building and maintaining reputation for each one. If an IP gets blacklisted, we swap it out immediately for a clean one—no impact to sender scores, no red flags with mailbox providers.

In other words, you don’t have to worry about IP reputation management. SiteGround handles it so your emails keep getting delivered even if something goes wrong behind the scenes.

Dedicated IP Addresses vs. Shared IP Addresses

Shared IPs are IP addresses used by multiple senders to send their emails. They work well for most businesses sending under 50,000 emails monthly. With shared IP addresses, you benefit from the established reputation that IP has built, assuming your provider manages it well. This works perfectly for smaller senders because building IP reputation requires consistent, high sending volume.

Dedicated IPs are IP addresses used exclusively by you—no other senders share them. They’re best for high-volume senders (typically 100,000+ emails monthly) who need full control over their reputation. You control your reputation completely, but you start from zero. 

Email List Quality

List quality determines whether you’re sending to real, engaged people who want your emails—or to invalid addresses, spam traps, and uninterested recipients who’ll hurt your reputation.

Building a clean email list of permission-based subscribers is your most valuable deliverability asset. A dirty list full of old, invalid, or non-consenting addresses will destroy your sender reputation no matter how good your infrastructure or content is.

Building and Cleaning Your List

Only add people who explicitly opted in to receive your emails. Never buy lists, scrape websites, or add people without permission.

Building Permission-Based Lists:

Use double opt-in whenever possible. This requires new subscribers to confirm their email address before being added to your list. It filters out typos, spam traps, and fake addresses while ensuring only genuinely interested people join your list.

Single opt-in, on the other hand, is faster but riskier—you’ll capture more addresses but also more invalid ones and people who didn’t fully understand what they were signing up for.

Regular List Cleaning:

Inactive subscribers tank your engagement metrics, which mailbox providers track closely. A smaller list of engaged subscribers delivers better results than a large list full of inactive addresses.

• Remove subscribers who haven’t opened emails in 6+ months
• Delete obviously invalid addresses (missing @ symbol, no domain extension)
• Suppress hard bounces immediately
• Remove spam complainers permanently

Understanding Bounces and Spam Traps

Two major threats to list quality are bounces and spam traps:

• Bounces signal deliverability problems. 
• Spam traps are email addresses designed to catch senders with poor list practices.

Hard Bounces

Hard bounces occur when the recipient email address doesn’t exist or is invalid. The receiving server permanently rejects delivery.

High hard bounce rates scream “spammer” to mailbox providers because spammers typically guess email addresses or use old, unverified lists. If you consistently hit hard bounces, providers assume you’re not managing your list responsibly.

At SiteGround, hard bounced addresses are immediately suppressed—they’ll never receive another email. If a campaign generates too many hard bounces, it’s paused automatically to protect sender reputation.

Soft Bounces

Soft bounces are temporary delivery failures, which can happen for reasons such as:

• The recipient’s inbox is full
• The email message too large
• The recipient’s server is temporarily down or overloaded
• Temporary blocks or maintenance

Soft bounces aren’t as damaging as hard bounces, but persistent soft bounces to the same address should eventually be treated as hard bounces.

When soft bounces occur, different email service providers take different approaches. SiteGround doesn’t give up—the platform makes multiple resend attempts, starting with frequent retries in the first few hours and then tapering off. This retry system is designed to successfully deliver email campaigns as soon as possible, keeping them on track to reach subscribers’ inboxes in a timely manner while optimizing email deliverability.

Spam Traps

Spam traps are email addresses that look real but exist only to catch senders with bad list practices. They come in three types:

1. Recycled spam traps: Previously active addresses that were abandoned, then repurposed as traps after a dormancy period
2. Typo traps: Common misspellings of popular domains (gmial.com instead of gmail.com)
3. Pristine spam traps: Addresses created specifically as traps, embedded in websites to catch scrapers

Hitting spam traps can blacklist your IP instantly because it proves you either bought a list, scraped websites, or haven’t cleaned your list in years.

How to Avoid Spam Traps

• Never buy or scrape email lists
• Use double opt-in to verify addresses
• Remove subscribers who haven’t engaged in 3-4 months
• Check for obvious typos in email domains

Managing Unsubscribes and Complaints

Not all negative responses are created equal:

• Unsubscribes are healthy—they remove uninterested people from your list. 
• Spam complaints are dangerous—they severely damage your reputation.

Unsubscribes

When someone unsubscribes, they’re telling you they don’t want your emails anymore. That’s valuable information. Keeping them on your list only generates poor engagement metrics and potential spam complaints.

At SiteGround, for example, unsubscribed contacts are automatically suppressed and won’t receive future emails.

Regardless of how your email marketing platform treats unsubscribes, it’s still important to monitor your unsubscribe rate per campaign. That’s because spikes indicate content problems or audience mismatch, so you can use this data to refine your email marketing strategy or segment your list better.

Make Unsubscribing Easy

Every email must have a clear, one-click unsubscribe option. Making it hard to unsubscribe frustrates people into clicking “Report Spam” instead—which is far worse for your reputation.

Spam Complaints

When recipients mark your email as spam, it sends a severe negative signal to mailbox providers. Too many complaints and your emails will be filtered automatically.

Common reasons for spam complaints:

• Recipient never agreed to receive your emails
• They forgot they signed up (poor welcome email, long gap before first campaign)
• No clear unsubscribe option visible
• Content doesn’t match what they expected when signing up

At SiteGround, anyone who marks emails as spam is automatically suppressed. If a campaign triggers excessive complaints, it’s halted mid-send to prevent further damage. Repeat offenses may result in account suspension.

Compliance Requirements

Different regions have laws requiring explicit consent for email marketing:

• GDPR (EU): Requires clear, unambiguous consent before adding anyone to your list
• CAN-SPAM (US): Requires clear sender identification, honest subject lines, and easy opt-out
• CASL (Canada): Requires express consent with specific documentation

Compliance isn’t just legal protection—it’s good for deliverability. Lists built with proper consent have higher engagement and lower complaint rates.

Recipient Engagement

Recipient engagement measures how subscribers interact with your emails—whether they open, click, reply, delete, or mark as spam.

• High engagement signals your emails are wanted, improving future deliverability. 
• Low engagement signals they’re unwanted, triggering spam filtering.

Opens, clicks, replies, and time spent reading all factors into deliverability algorithms. 

On the other hand, immediate deletes, spam reports, and consistent non-engagement tell providers your emails aren’t valuable.

Why Engagement Matters

Email providers use engagement as a primary signal for inbox placement because it reveals whether recipients actually want your emails.

Traditional spam filtering looked at content and sender authentication. Modern filtering uses AI and machine learning to analyze behavior patterns across millions of emails. 

Gmail, Yahoo, and Outlook, for example, use modern filtering. Their algorithms track:

• Open rates: Apple’s Mail Privacy Protection (2021) makes this less reliable for iOS/Mac users, but it’s still tracked for other email clients
• Click-through rates: Whether recipients click links in your emails
• Deletion speed: How quickly emails are deleted without being read
• Replies: Whether recipients reply to your emails
• Folder movements: Whether recipients move emails from spam to inbox (or vice versa)
• Engagement over time: Whether recipients consistently interact with your emails or ignore them

These metrics give mailbox providers an overall view of engagement. High engagement tells providers: “People want these emails, prioritize them.” Low engagement says: “Nobody cares about these, filter them out.”

This is why bought lists never work—those recipients didn’t ask for your emails and won’t engage, tanking your reputation immediately.

What to Do About Low Engagement

Monitor your engagement metrics regularly to identify warning signs:

• Declining open rates campaign over campaign
• Low click-through rates (under 2-3%)
• High delete rates without opens
• Increasing unsubscribe or spam complaint rates

If you’re seeing low engagement, adjust your approach:

Sending less often can actually improve engagement. If weekly emails aren’t working, try bi-weekly or monthly for less engaged subscribers.

Focus your higher-frequency campaigns on subscribers who consistently open and click. They’re your deliverability champions and the ones who actually want to hear from you more often.

The goal isn’t to email everyone constantly—it’s to email the right people with relevant and personalized content that they actually want at a frequency they appreciate.

Segmentation and Re-Engagement Strategies

Send different content to different audience segments based on interests, behavior, and engagement level. This increases relevance and engagement for everyone.

This is the core principle of STP marketing (Segmentation, Targeting, Positioning)—you divide your audience into meaningful groups, target each with relevant content, and position your message to resonate with their specific needs. In email marketing, this approach directly impacts deliverability because more relevant emails generate better engagement signals.

Segmentation Strategies:

Don’t send every email to your entire list. Segment by:

• Interests/preferences: Send product-specific content only to people interested in those products
• Engagement level: Send more frequently to highly engaged subscribers, less to occasional openers
• Purchase behavior: Different messaging for customers versus. prospects
• Demographics or firmographics: Tailor content to different audience characteristics

Better targeting means better engagement, which directly improves deliverability.

Re-Engagement Campaigns:

Identify subscribers who haven’t opened emails in 3-6 months and send targeted re-engagement email campaigns:

• “We miss you” messaging
• Special offers or incentives
• Preference center to update interests
• Simple “Do you still want to hear from us?” question

If they don’t respond to re-engagement attempts, remove them from your list. Continuing to email unengaged subscribers damages your metrics and reputation for zero benefit.

Sunset Policies:

Create a systematic process to remove chronically unengaged subscribers:

• 90 days no opens: Tag as “low engagement”
• 120 days: Send re-engagement campaign
• 150 days: Final re-engagement attempt
• 180 days: Remove from active list

This keeps your list healthy and your engagement metrics strong.

Email Content Best Practices

Your content determines whether recipients engage with your emails or mark them as spam. Even a perfect technical setup won’t save poorly crafted content.

Content quality affects deliverability in two ways: directly through spam filter algorithms that scan for trigger patterns, and indirectly through recipient behavior that signals engagement or annoyance.

AI-Generated Content

With AI tools making it easy to generate email content at scale, mailbox providers have gotten smarter about detecting generic, mass-produced messages. In 2025, spam filters analyze:

• Whether your content sounds templated or formulaic
• If multiple email senders are using identical or near-identical phrasing
• Whether your emails show genuine personalization or just token customization

The solution isn’t to avoid AI tools—it’s to use them thoughtfully while considering AI ethics in your marketing practices:

• Edit AI-generated content to add your unique voice and specific examples
• Include genuine customer stories, real data from your business, or personal insights
• Avoid sending AI-generated emails without substantial human editing
• Use effective ChatGPT prompts for targeted content, not generic templates
• Test your content to ensure it doesn’t read like every other promotional email

Authenticity wins in 2025. Subscribers (and spam filters) can spot generic content instantly.

Subject Lines and Avoiding Spam Triggers

Subject lines should be clear, honest, and relevant. Misleading or gimmicky subjects trigger both spam filters and recipient complaints.

Subject Line Best Practices:

• Keep under 50 characters for mobile readability
• Be specific about email content—no clickbait
• Avoid ALL CAPS and excessive punctuation!!!
• Personalize when relevant (use names or company names)
• Test different approaches to see what resonates

Spammy Subject Lines Triggers to Avoid:

• Excessive use of “free,” “guarantee,” “no obligation”
• Heavy promotional language: “act now,” “limited time,” “urgent”
• Financial terms: “credit card,” “cash,” “income”
• Sensationalist phrases: “amazing,” “incredible deal”

Using these words occasionally won’t destroy you, but stacking them makes you look like spam. Keep language natural and conversational.

Email Body Content:

• Avoid too many images with little text (high image-to-text ratio)
• No hidden text or deceptive formatting
• Include proper grammar and spelling—errors trigger filters
• Don’t use URL shorteners excessively (masks destination, looks suspicious)
• Test all links before sending

Not sure how to nail your email content? Follow these email copywriting best practices to avoid spam filters and keep readers engaged:

Design and Personalization

Clean, mobile-friendly design with personalized, relevant content drives engagement and avoids spam filters.

Design Best Practices:

• Mobile optimization is non-negotiable: Over 50% of emails are opened on mobile devices. Use responsive design that adapts to screen size. Test on multiple devices before sending.
• Keep it clean: Avoid cluttered designs with too many fonts, colors, or competing calls to action. Simple, professional layouts perform better and avoid overwhelming recipients.
• Balance images and text: Too many images with little text looks like spam. Aim for at least 60% text content. Always include alt text for images.
• Include plain-text versions: Some email clients don’t render HTML well, and some spam filters prefer seeing a plain-text alternative included.

Personalization:

Basic personalization (using recipient’s name) is table stakes. Go deeper:

• Use recipient names: Basic personalization is table stakes, but it’s still essential.
• Reference past behavior: Mention past purchases or browsing activity to show you’re paying attention.
• Acknowledge lifecycle stage: Treat new subscribers differently than loyal customers.
• Tailor recommendations: Use their interests and preferences to suggest relevant products or content.

Personalized emails generate higher engagement, which improves deliverability for future campaigns.

Consistency:

Maintain consistent sending schedules so subscribers know when to expect your emails. Random, unpredictable sending patterns lower engagement and can trigger filters if volume suddenly spikes.

General frequency guidelines:

• Daily emails: Only works for news/media companies or if subscribers explicitly opted in for daily content. High risk of fatigue.
• 2-3 times per week: Suitable for ecommerce with frequent promotions or content-heavy businesses. Requires strong segmentation.
• Weekly: The sweet spot for most businesses. Predictable, manageable, and maintains engagement without overwhelming.
• Bi-weekly: Works for B2B, consulting, or businesses with less frequent updates. Lower fatigue risk.
• Monthly: Minimum recommended frequency to maintain list warmth and recognition. Less than this and subscribers forget who you are.

Warning signs you’re sending too often:

• Unsubscribe rate increases with each send
• Open rates declining campaign over campaign
• Spam complaint rate rising above 0.1%

SiteGround’s Preventive Campaign Checks

Before sending any campaign, SiteGround’s AI examines it for spam signals, phishing patterns, and policy violations, stopping problematic campaigns before they hurt your reputation.

Navigating spam filters and deliverability rules is complex. SiteGround’s advanced AI scans every campaign pre-send, evaluating:

• Likelihood of spam folder placement
• Content that violates usage policies
• Phishing or malicious patterns
• Authentication and technical setup issues

If issues are detected, the team manually reviews and alerts senders before the campaign goes out, giving them the chance to fix problems that would damage reputation.

For new Email Marketing users, SiteGround manually reviews the first three campaigns to help start with strong deliverability and avoid common mistakes.

Monitoring Your Deliverability

Track key metrics to identify deliverability problems early, before they become reputation-damaging crises.

Reactive deliverability management means waiting until campaigns fail. Proactive management means monitoring trends and fixing small issues before they escalate.

Key Metrics and Troubleshooting

What to Track and What the Numbers Mean:

• Bounce Rate: Total bounces divided by emails sent. Hard bounces over 2% indicate list quality problems. Soft bounces over 5% may indicate technical issues or content size problems.
• Spam Complaint Rate: Complaints divided by emails delivered. Anything over 0.1% (1 complaint per 1,000 emails) is concerning. Over 0.3% and you’re risking serious reputation damage.
• Unsubscribe Rate: Unsubscribes divided by emails delivered. 0.2-0.5% is normal. Sudden spikes indicate content or targeting problems.
• Open Rate: Opens divided by emails delivered. While less reliable post-iOS privacy changes, declining trends still signal engagement problems.
• Click-Through Rate: Clicks divided by emails delivered. Low CTR means your content isn’t resonating or your targeting is off.

Inbox Placement Rate: Percentage of delivered emails that reached the inbox versus spam folder. This requires specialized testing tools. Aim for 95%+.

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Common Deliverability Problems and Solutions:

• Sudden deliverability drop: Check if your IP was blacklisted, authentication records broke, or a recent campaign triggered high complaints.
• Consistently low open rates: List is stale or disengaged. Implement re-engagement campaigns and sunset policies.
• High bounce rates: List needs cleaning. Remove invalid addresses and verify your acquisition sources.
• Emails going to spam folder: Check content for spam triggers, verify authentication is set up correctly, improve engagement through better targeting.
• Increasing spam complaints: Review whether you have proper consent, make unsubscribe more visible, ensure content matches subscriber expectations.

Set up automated alerts for metric thresholds so you catch problems immediately rather than discovering them after multiple campaigns fail.

Your Deliverability Action Plan

Mastering email deliverability requires ongoing attention to infrastructure, authentication, list quality, and content. 

Follow this roadmap to build and maintain strong deliverability:

Immediate Actions (Do Now):	Set up SPF, DKIM, and DMARC authentication recordsImplement double opt-in for new subscribersAdd clear one-click unsubscribe to all emails Clean your list of obvious invalid addresses and hard bounces
Monthly Maintenance:	Review engagement metrics and identify declining trendsClean inactive subscribers (6+ months no opens)Test email campaigns before sending to full listMonitor blacklist status of your sending IPsAnalyze spam complaint rates and adjust content/targeting
Quarterly Deep-Dive:	Audit your entire email list healthReview and update audience segmentsTest inbox placement rates with deliverability toolsEvaluate and refresh email templates for mobile optimizationRun re-engagement campaigns for inactive segments
Best Practices Always:	Never buy or scrape email listsSend consistently—no sudden volume spikesKeep content relevant through segmentationMake unsubscribing easyMonitor recipient engagement patternsWork with reputable email service providers

Ready to Maximize Your Email Deliverability?

Email deliverability isn’t something you set up once and forget—it requires ongoing attention to infrastructure, authentication, list quality, and content. But you don’t have to manage it all alone.

What SiteGround handles for you:

• 98.80% delivery rate with redundant infrastructure across multiple data centers
• Automatic SPF, DKIM, and DMARC setup for domains we manage
• 24/7 IP reputation monitoring and blacklist management
• AI-powered campaign scanning before every send
• Gmail and Yahoo 2024 compliance built-in
• One-click unsubscribe functionality included automatically

Whether you’re sending your first campaign or your ten-thousandth, deliverability is the foundation that makes everything else possible. The difference between a message that reaches the inbox and one that disappears into spam can be the difference between a sale and a missed opportunity.

Start sending emails that actually get delivered.

This article was originally published in March 2024, and then updated in October 2025.