Why Your Emails Are Being Blocked & What to Do About It

Table of Contents

• Why are your emails being blocked?
• Reason #1: Your emails aren’t authenticated
• Reason #2: You’re sending content that looks spammy
• Reason #3: You’re hitting spam traps
• Reason #4: Your emails are blocked by an ISP
• Reason #5: You’re hitting custom spam filters
• Reason #6: You’re experiencing technical issues
• Reason #7: You’re repeatedly sending to invalid email addresses
• Get better emails to more people

If you’re an email marketer, you know the frustration of seeing your carefully crafted emails end up in the digital void instead of the inbox. But why does this happen? More importantly, how can you keep it from happening again (or ever)? Below, we’ll dive into the nitty-gritty of email blockage, why it happens, and share actionable tips to keep your emails out of digital purgatory and into their intended inboxes.

Why are your emails being blocked?

First, let’s define our terms. A blocked email happens when an Internet Service Provider (ISP), Mailbox Provider (MBP), or client email server prevents your email from reaching a subscriber’s inbox. Think of it like a digital bouncer turning you away at the door. This can happen for a variety of reasons, some obvious and some not so much. That said, it’s always a good idea to dig into these underlying reasons so you can avoid the dreaded block and keep your email deliverability in check.

Reason #1: Your emails aren’t authenticated

Imagine an uninvited guest at a party—that’s what an unauthenticated email looks like to an ISP. They’re wary of emails that can’t prove they’re from who they say they’re from. Without robust authentication, bad actors can impersonate your domain, sending malicious emails that not only damage your reputation but also lead to data breaches that harm your subscribers.

How to fix it: Implement the right protocols

• Avoid email authentication failures by implementing protocols like SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting, and Conformance). These protocols verify your emails’ legitimacy and prevent impersonation.
• Regularly monitor your authentication records and update if needed to maintain their effectiveness.

Reason #2: You’re sending content that looks spammy

While the concept of “spam trigger words” is outdated, subscribers will manually mark your emails as spam if they include using too many sales-y phrases, excessive capitalization, and multiple exclamation points!!! (see what we did there?).  If recipients frequently mark your emails as spam, MBPs will take note and the consequences could be dire. Your domains or IP addresses could be blocklisted, your emails may be automatically filtered to spam folders, and your sender reputation could be damaged.  Solve for this by keeping your content professional and well-balanced. If you’d like to be recognized and rewarded for being a reputable sender, consider Validity’s exclusive Sender Certification program. In the meantime, follow the below tips.

How to fix it: Improve your content

• Avoid overly promotional language, excessive capitalization, and too many exclamation points or emojis. Instead, opt for a more natural and conversational tone.
• Test your email templates to ensure they work across all email clients, are mobile-friendly, and follow accessibility best practices.
• Segment your subscribers based on their demographic information and past shopping behavior and approach them with highly personalized and relevant content tailored toward their needs.

Reason #3: You’re hitting spam traps

A successful marketing strategy relies heavily on maintaining a high-quality email list. Internet Service Providers and blocklist operators regularly use spam trap email addresses to flag undesirable behavior, Falling into one can result in significant repercussions. (Get an overview of the different types of spam traps and how they impact your deliverability here.)

How to fix it: Practice list hygiene

• Regularly clean your email list to remove unengaged or invalid subscribers.
• Avoid buying lists (as opposed to growing them organically) as they may include spam trap emails.
• Enable double opt-in confirmation and include a clear and easy-to-find unsubscribe link in your emails to allow users to opt out if they wish. 
• Check your feedback loops so you can analyze which messages are receiving complaints and strategize how to fix the problem.
• Check your email or IP address to see if you have been added to any email blocklists using the free email blocklist lookup tool on Sender Score.

Reason #4: Your emails are blocked by an ISP

As mentioned above, an ISP might block your emails if they suspect malicious activity or if you’ve been blocklisted. This can happen due to poor sending practices or being associated with other spammers. To avoid seeing your email blocked by servers, try:

How to fix it: Stay on top of your sender reputation

• Monitor your IP reputation scores through Sender Score, a free service provided by Validity.
• Maintain consistent sending volumes and avoid sudden spikes in email activity.
• If you’re a new sender, make sure you warm up your IP to avoid looking like a bad actor.

Reason #5: You’re hitting custom spam filters

Businesses often set up their own spam filters to keep unwanted emails out. These can be more aggressive than standard ISP filters. To get past these, understand the specific filters your audience’s companies might be using and tailor your emails accordingly. It’s a bit like customizing your approach for different clients.

How to fix it: Get subscriber buy-in

• The best way to avoid spam filters in this scenario is to get added to your recipients’ address books—this serves as a VIP pass that ensures you always get access to their primary inbox.
• Allow recipients to customize how often they hear from you through an email preference center that allows them to opt in and out of emails and select a cadence.

Reason #6: You’re experiencing technical issues

Sometimes, it’s not about content or reputation, but technical gremlins. This can include server issues, incorrect email settings, or problems with your email service provider. Regularly check your email setup and monitor your deliverability metrics to catch these issues early.

How to fix it: Follow best practices

• Follow email design best practices and regularly test your emails to identify deliverability issues.
• Regularly audit your email infrastructure for any technical issues like incorrect email settings or server problems.
• Avoid email attachments as they often increase the email size and face greater scrutiny from mailbox providers looking for potential viruses or malicious content.
• Be sure to optimize your images to be a smaller file size, and include alt-text for each image you include. Test your emails across different email providers to ensure your email appears how you intend.

Reason #7: You’re repeatedly sending to invalid email addresses

Consistently sending emails to addresses that no longer exist or are incorrect is a big red flag for MBPs. Clean your email lists regularly to avoid this pitfall.

How to fix it: Validate your email list

• Implement list hygiene practices like regularly validating email addresses and removing inactive or invalid ones.
• Use email verification tools like BriteVerify to ensure the validity of email addresses before adding them to your list.

Avoid email blockage and get better emails to more people

Ultimately, avoiding email blocks is all about being a good digital citizen—authenticate your emails, respect your audience, and keep your tech in check. With these tips, you’ll be on your way to stellar deliverability rates and stronger email performance. But to set yourself up on the fastest track to success, check out Validity Sender Certification.  As the industry’s most comprehensive email allowlist, Sender Certification helps senders detect and prevent deliverability threats and get more eyes on their emails. To get started, see if you’re pre-approved today.