Welcome to the third and final installment of our email deliverability series! In parts one and two, we discussed different types of emails, how to keep your emails from getting labeled as spam, why DNS records are crucial, and we demystified the secret sauce behind SMTP. But we didn’t just cover the technical details; we also shared best practices on sending emails that get read. 

We’re taking it up a notch in this third installment by sharing some advanced email strategies. We’ll discuss sender reputation, why it’s crucial to build a good reputation as an email sender, guidelines for email content, and the relationship between SMTP and email deliverability- let’s get started.  

Content Significance 

The most important thing for ensuring emails reach their destination is what’s inside the email itself; however, it’s not just about the words but also about who’s sending it, how it looks, and how easy it is to read. Internet Service Providers (ISPs) look at all these things to decide if an email is genuine or might be harmful. 

• Sender Reputation: If an email sender has a history of sending spam or engaging in malicious activities, their emails are more likely to be flagged as spam or blocked. We’ll dive deeper into this later in the article.  
• User Engagement: Emails that receive high open rates, click-through rates, and positive responses are considered valuable and are more likely to land in the inbox. Conversely, emails with low engagement may be marked as spam. 
• Content Quality: Overly promotional or suspicious content, excessive use of specific keywords, and poorly formatted emails can trigger spam filters. 

How ISPs Decide What to Do With Emails 

ISPs have a significant role in determining the fate of incoming emails. They employ complex algorithms and filtering mechanisms that take various factors into account to distinguish legitimate emails from spam. Some key elements in these algorithms include: 

• Sender Authentication: ISPs verify SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail) records to check if emails come from legitimate sources. These protocols help prevent email spoofing and phishing. 
• Spam Reports and Folders: User-generated spam reports are crucial. When multiple users flag an email as spam, it raises concerns with ISPs and can harm sender reputation. Potential spam emails are often placed in recipients’ spam folders, reducing visibility. 

• Blocklists or Bouncebacks: ISPs maintain lists of known spammers and malicious IP addresses. Emails from these sources are likely to be filtered out. When an email is rejected by the recipient’s ISP, a bounceback message indicates the reason for rejection, offering insights for senders to enhance email deliverability. 
• Safelisting: ISPs offer safelisting services that allow trusted senders to bypass specific filtering checks. 
• Content Analysis: Algorithms scrutinize email content for potential spam indicators, such as excessive use of trigger words, suspicious links, or attachments. 

Common Trigger Words 

It’s also worth noting that certain words or phrases can raise suspicions and trigger spam filters. While the list of trigger words may vary among ISPs, some common ones include: 

• Free 
• Win 
• Discount 
• Guaranteed
• Act now 
• Cash 
• Congratulations 
• Call now 

While these words alone may not necessarily lead to an email being marked as spam, their use with other spammy elements can contribute to email deliverability issues. 

Sender Reputation 

Think of sender reputation as your email credibility score. It’s the judgment call made by ISPs and email recipients regarding your trustworthiness and reliability as an email sender. This score significantly impacts whether your emails reach the inbox or are sent to the spam folder. Your sender reputation relies on bounce rate, sender history, and engagement.  

For example, say you’re sending newsletters for a local gardening club. Your sender reputation depends on consistently sharing valuable content to engage recipients, boosting trust with ISPs. Sending irrelevant content to an uninterested audience can harm your reputation and lead to emails being marked as spam. 

Factors That Affect Sender Reputation 

• Bounce Rates: Bounce rates are a critical indicator for Email Service Providers (ESPs).  
• Hard Bounce: These occur when sending emails to non-existent or invalid email addresses.  
• Soft Bounce: Soft bounces are temporary issues like a full mailbox or a server problem. 
• Sender History: Your sender history tracks your email behavior, like the number and pace of your emails.  
• Engagement: Engagement gauges your email campaign’s success through metrics like open and click rates. 

Overall, these factors significantly impact your sender’s reputation, affecting your emails’ deliverability. Understanding and managing these factors is crucial for successful email marketing. 

The Impact on Deliverability 

A poor sender score means your emails will unlikely reach your subscribers, but it’s still possible. Being labeled as a spam sender can hurt your business and even lead to your domain being blacklisted, which means your emails won’t be delivered. 

A Deeper Dive Into SMTP 

SMTP, which stands for Simple Mail Transfer Protocol, is the technology that makes sending emails on the internet possible. It’s like the road system for email messages. Just as roads help cars get from one place to another, SMTP allows emails to travel from the computer where they are sent (the sender’s email server) to the computer where they are received (the recipient’s email server). 

If you’d like a refresher on SMTP, check out part one of the email deliverability series.  

SMTP and Email Deliverability 

A poorly configured SMTP server has the potential to tarnish your sender reputation, thereby increasing the risk of your future emails being designated as spam or summarily denied. On the other hand, a properly diligently optimized SMTP server substantially boosts the probability of your emails seamlessly arriving in recipients’ inboxes. 

Importance of Optimization 

Optimizing mail settings and practices is crucial for maintaining high email deliverability rates. Here are some key optimization considerations: 

• Verification: Configure SPF, DKIM, and DMARC DNS records. While these records are typically set up on the DNS server, in practice, some configuration may be necessary on both the DNS and SMTP servers. 
• Reputation Management: Monitor and maintain a positive sender reputation to avoid being blacklisted by ISPs. 
• Message Queue Management: Implement efficient message queuing systems to handle email delivery promptly and prevent bottlenecks. 
• Feedback Loops: Subscribe to ISP feedback loops to receive reports on user complaints and adjust email-sending practices accordingly. 
• Encryption: Use TLS (Transport Layer Security) to secure email communication between servers, enhancing security and trustworthiness. 
• IP Warm-Up: Gradually increase email sending volume when using a new IP address to build a positive sending reputation. 

Perfecting Email Content and SMTP Configuration 

Indeed, it’s clear that what you put in your emails greatly influences whether they’ll be marked as spam. The content can affect your email campaign’s performance, signaling to ISPs that your sender reputation score should drop. A low reputation score increases the chances of your emails ending in the spam folder. But it’s not just about content; setting up SMTPs is also crucial. If you have questions about improving your emails, contact us at ThoughtProcess Interactive!