Email Deliverability

Email Deliverability

February 7, 2022

Businesses depend on email to deliver important information to their customers, employees, stakeholders, and others. Yet it’s amazing how many of these messages don’t get to their recipients. Instead, spam filters and black lists as well as misconfigured DMARC, SPF, and DKIM records prevent them from being delivered.

These technologies exist because of the overwhelming amount of spam landing in inboxes every single day. Believe it or not, it’s estimated that 122.3 billion spam email messages, fully 85% of the world’s daily email traffic, are sent daily. That mind-boggling statistic forced the development of methods to differentiate between valid and spam messages. To make matters worse, many of these spam email messages deliver viruses or ransomware, both of which can be dangerous to individuals and infrastructure. It’s no longer viable for spam messages to be ignored–the possibilities of damage are too great.

The ramifications for reaching customers or prospects should be obvious. Getting a message past the multiple defenses put in place for each inbox requires that you understand how spam blocking technology works and what you can do to get around it.

Misunderstanding email deliverability reduces the chance of you reaching your audience, sometimes to where only a few percent of your customers will find your messages in their inbox. The quality of your content doesn’t matter if no one gets the chance to read it.


Have you ever received an email message that appeared legitimate because it seemed to be from the domain of someone you knew? That’s called email spoofing, which means a spammer created a message that “pretended” to be from someone else. The SPF standard is designed to prevent this from happening. However, if you misconfigure your SPF definition, your messages

will automatically be treated as spam long before they hit inboxes. If your messages don’t appear to be reaching your audience, check the SPF definition.


Another technology to help reduce the vast amount of spam is known as DMARC. Like SPF, these are defined on a domain basis and their purpose is to control what happens if a message cannot be authenticated–if the sender is not valid. DMARC indicates whether the faulty message should be quarantined, rejected, or ignored. This is another instance where your messages may be rejected long before they reach users’ inboxes.


DKIM (Domain Keys Identified Email) is another method used to figure out the validity of email messages. DKIM causes a signature to be added to each message. The email server servicing the recipient confirms the signature before accepting the message. Misconfigured DKIM records on the sender domain can cause messages to be erroneously rejected.

Black List

So far, we’ve talked about mechanisms defined on the domain name to help an email server determine that a message is from a valid sender. Several organizations run black lists, each of which contains domain names or IP addresses of spammers or suspected spammers. If your domain or IP address winds up being listed in one of these black lists, most email servers will reject your messages.

There are several ways your server can get listed on these black lists:

1. You’ve been reported as sending spam by several individuals.

2. Automated bots decide that you’ve been sending spam.

3. Someone else on the same IP block as your server has been identified as sending spam.

4. Your email provider has been identified as sending spam.

In the last two cases, your only recourse may be to move your server to another IP block or change email providers.

Spam Filters

Most email clients come packaged with spam filtering components to remove the obvious spam messages. Based on user preferences, suspected spam may be deleted or filed in folders. These filters review each message to calculate a score. Higher scores indicate a higher possibility of

spam. To get around this, ensure your messages are properly formatted and don’t read like spam.

The last line of defense are spam filters set up by users themselves. Most email clients allow rules to be defined that automatically delete or file messages based on sender, subject, or other criteria. Users can define rules to help reduce clutter in their inboxes; this can cause your messages to never be seen. To prevent this, make sure your messages are targeted properly and are valuable to your audience.


The vast amount of spam messages sent every day requires a vigorous defense to prevent inboxes from being overwhelmed not just with unwanted emails, but from the threat of viruses and ransomware. However, this also requires you to target your emails correctly and ensure that they have information that is useful and desired by your audience. New technologies such as SPF, DMARC, and DKIM help in the fight against spam, but when misconfigured will keep your valuable messages from reaching their recipients.

With a little diligence you can increase the odds that your emails will be read and acted upon by your audience.

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