8 Reasons Why Your Email Deliverability Lets You Down

When I first heard the term “email deliverability”, I didn’t think it was important for my marketing campaigns. After all, my marketing emails getting successfully delivered was my only goal. Why should I care about it then, right?

But then my numbers started to go down gradually and eventually came to a crawl. I tried feverishly try to bring them back, I tested many elements of my emails to bring its previous glory back to the dashboard.

But nothing worked.

If it performs well on numbers and gives you the results you were expecting, you might not even notice where the campaign is failing. You might not even care about email deliverability.

However, email deliverability is an extremely crucial factor that can make or break your email marketing campaigns. This step precedes the next crucial incidence of having engaged users.

Before you take the next step, first see if low email deliverability is the culprit for your underperforming email campaigns.

Clarifying the difference between email delivery and email deliverability

The difference is subtle but very important. To help you understand this difference, I am going a little bit technical. So, please bear with me.

Email is delivered first to the server and then to the client.

Say, you have a Gmail account. My marketing emails to you will first get delivered to Gmail servers, which is called email delivery.

At the server, it gets processed and checked for spam. The Gmail server checks if my email contains legitimate information and is not a virus or a spam message.

Once the server okays it, the email is delivered to your Gmail inbox, generally referred to as ‘subscriber inboxes’. This is called email deliverability.

This is how the email delivery system works.

This is how you can visualize the whole process

Definition of Email Deliverability
The Definition of Email Deliverability

(Source: TavanoTeam.com)

From this definition, it’s obvious that email delivery is not everything. Without high deliverability, your email campaigns have no scope of performing well.

If your marketing campaigns got delivered to the users’ inbox early on in the campaign, the email servers didn’t find anything spam in your emails.

Then due to one or more of the factors highlighted below, the servers started flagging your emails for spam. While emails were getting delivered to the servers, the deliverability rate kept dropping as the servers started rejecting your emails as spam.

Low email deliverability means emails not reaching the final users. Hence the drop in engagement rates, email opens, and CTR.

What Could Be Going Wrong If You Have Low Email Deliverability

(Source: Remarkety.com)

Email deliverability is an under-the-hood stat that’s not immediately apparent. In fact, it’s not just a single factor; lots of small moving parts in the email marketing mechanism can lower your email deliverability. Your goal should be to improve email deliverability.

Let’s see what those factors are.

1. Your sender score may be too low

SenderScore.org gathers data from multiple sources and assigns your IP or your domain a score that indicates your sender reputation.

A sender score of less than 70 is indicative of background work that you may need to improve your sender reputation.

If your email stats are falling, checking the sender score is a good way to get started with the troubleshooting.

2. Your email server is not authenticated

Email servers run email authentication protocols to make sure the senders are not spamming or engaging in phishing. If you don’t implement these protocols, the receiver server will mistake you as a malicious sender. Your emails could land in the spam folder or might not be delivered at all.

Email Authentication
Authenticate your email servers before you start your first email marketing campaign

(Source: Automizy.com)

Here are the three primary email authentication protocols:

  • SPF (Sender Policy Framework)
  • DKIM (DomainKeys Identified Mail)
  • DMARC (Domain Message Authentication Reporting and Conformance)

Sender Policy Framework (SPF)

SPF is a very basic email authentication protocol. In SPF,  the receiving email server pings the originating server to ask for a list of approved senders. If the sender is not on that list, it is marked as SPAM because then there’s a possibility of impersonation.

In short, the receiving server directly asks your domain server if you are an approved sender. You need to ensure your domain server (DNS) has an SPF record with your name.

If you use an email service provider, you can ask your support team to clarify the details of SPF on their server to check if that might be a source of the problem.

Here is a blog for how to implement SPF on your own email server: https://blog.returnpath.com/how-to-build-your-spf-record-in-5-simple-steps

Socketlabs also hosts an article on best practices with SPF.

DomainKeys Identified Mail (DKIM)

Another email verification protocol is DKIM, which uses encryption using a public key and a private key. It changes the way an email is encoded for transmission over the internet.

DKIM-encrypted messages are encoded with two different keys. One is a private key that encodes only the email body and is available only with two parties – the sender and the receiver. No one else possesses that key and hence no one can decrypt the email to see its contents.

The email header (a separate block with additional meta-information about the content) is encrypted with a public key. The receiving server verifies the authenticity by using the public key to decrypt the header. This ensures the contents of the email have not been tampered with and the source of the email is a legitimate sender.

To implement DKIM on your email server, follow the steps mentioned in this blog.

Domain Message Authentication Reporting and Conformance (DMARC)

DMARC has the combined power of SPF and DKIM. The receiving server will verify if the email follows SPF and DKIM policies. Offending emails and senders will be reported back to sending servers as offenders. This makes DMARC stricter than the other two.

If you use a mass email sending service (like that of an ESP), do ask the support team about their DMARC implementation.

3. You didn’t warm up your IP in the initial days of your first email campaign

IP warm-up means starting with a low volume of approximately 100-500 email sends and then gradually increase it to full steam with tens of thousands of emails per month.

Your fresh IP address has no sender reputation for these servers to judge the quality of your emails. Without a disciplined schedule, you will end up bombarding the server with a large volume emails before the server has enough data to assign your IP a sender reputation. If you send bulk emails from a brand-new IP, the server will see your emails as spam because it doesn’t know what to make of them.

Effect of IP Warm-up
IP Warm-up is the most basic way to ensure you don’t get blacklisted just for being on a new email server

(Source: Juvlon.com)

A balanced IP warm-up schedule allows you to get into the good books of popular ESPs like Gmail or Yahoo.

The warm-up period gives all receiving servers enough time and data to analyze your sending behavior and monitor your engagement levels. During the warm-up, you can monitor the campaign to gather data for detailed optimization later on.

To conduct a successive warm-up, start with an internal email list (personal email addresses). Start by sending welcome emails to your own employees’ personal email as a test. Try to get them to respond to your emails and click on CTR (the more engagement, the faster is the learning of their receiving server). If the email does drop into someone’s spam box, ask them to move it to the original inbox.

After your internal emails, start with your “most engaged” subscribers. You can send your emails to those who have freshly subscribed, in the absence of sufficient engagement data.

Now, start sending emails to your lesser engaged subscribers working your way back to the least engaged ones.

If you notice a considerable drop in open rates or engagement rates, slow down and let the server catch up with your IP.

Also, be sure to send a similar number of emails to every ISP each day.

4. You don’t trim your email list regularly

Sending too many emails to invalid addresses or having too many unsubscribes in a short span of time – this is a bad sign for your IP reputation. That’s why email list cleanup must be conducted at least twice every year.

Email List Cleaning
Email List Cleaning is important for the health of your email marketing campaign

(Source: itracmarketer.com)

Even If users willing subscribed to your list, they may mark spam if the user doesn’t remember subscribing to your list.

What do you think the user will do if they know that they never subscribed for sure?

They will immediately mark your email as spam – IN BOTH CASES.

These are unique problems and require innovative solutions.

For the first one, add a layer of authentication in the first email; you send to your brand-new subscribers. Ask them to click to a link for verifying their email address so they remember when they subscribed to your list.

The second problem occurs when you buy a third-party email list without trying to cultivate a relationship and send emails without asking users’ consent. To stop being marked spam, stop buying the email lists; most of them won’t convert anyway.

If they don’t mark you as spam on the first email, there is no guarantee that you will be a permanent member of their inbox.

Remove the role accounts like “sales@”, “info@” and so on as the servers may consider it spam. These email addresses are usually entered by competitors; they may be fake addresses or linked to temporary inboxes.

Remove invalid email addresses that do not exist but still contribute to your hard bounces regularly.

Your engagement metrics are not just important to email servers, but to your own marketing campaigns as well. If you have a large number of inactive subscribers, the denominator in every email marketing metric will be higher than what it would be without those inactive emails.

So trim these inactive emails from your list for the sake of the health of your own email campaign.

5. You make no effort to avoid spam traps

How are massive drug busts successfully executed?

You lure the drug dealers by pretending as their potential client and catch them in the act.

Email providers have a smart way of catching these spam attackers. They send a massive volume of emails to collapse a network by using purchased email lists; these lists are not maintained. They don’t care as they just want to bombard the system with email traffic.

So, buying email lists is essentially akin to buying clothes from a defective clothes sale, without any knowledge of where these defects are. If you want to look good at a party, you would want to avoid these defective clothes. Likewise, for a successful email campaign, you must avoid buying these defective email lists.

In short, email providers simply plant an old (and inactive) email address (i.e. the spam trap) and plant it in these networks where spammers buy their lists.

Two Types of Email Spam Traps
Two Types of Email Spam Traps

(Source: emailoversight.com)

These spammers will attempt to overload the email system with massive traffic. But they will be caught and blocked by the email provider.

If such a spam trap has found its way into your email list, chances are one of the major email networks has mistaken you for a spammer. They have blocked your emails resulting in the death of an otherwise highly active email marketing dashboard. It may happen later if it hasn’t happened so far.

Being caught in a spam trap leads to directly being blacklisted. This affects your sender reputation and as a result of that, your email deliverability goes down in the dumps.

To avoid these spam traps:

  • Stop buying lists
  • Always use double opt-in email
  • Regularly run “list cleaning” campaigns. Besides identifying spam traps and invalid email addresses, these campaigns also allow you to identify subscribers who no longer want to receive emails.

6. Your IP might have already been blacklisted

Chances are some parts of your email campaign may have gone off track and committed an error that landed you in a blacklist. You will then fail the email reputation check.

To check if your email server is blacklisted, head over to DNSBL website and check for IP of your email server. The site tells you which blacklists mention your IP.

If it is on a blacklist, it may not be an accident. On a shared email server, other senders may be committing one of the mistakes that got the IP blacklisted.

Find which blacklists are listing your IP and talk to them to see what you can do to get off the blacklist.

As a worst-case scenario, you may have to get yourself a dedicated IP or change to a reputed email service provider.

For a more thorough process, check out IP Unblacklisting Guide by WhatIsMyIPAddess.com.

7. Your opt-out process is very complicated

Your emails may be regularly marked as spam because you have not paid attention to your opt-out process. This is true because users will find marking your email as spam much easier if they can’t unsubscribe in one click.

Make sure there is an “Unsubscribe” link at the end of every email you send. It should be clearly visible; don’t make color or font size adjustments to hide them. This is a mandatory privacy requirement under GDPR laws if you serve EU citizens.

And when the link is clicked, the originating email address should be immediately removed from the list. This removal should be communicated to the user in clear and bold letters to the user or they may immediately mark you as spam.

But then again, you also want to understand why they are unsubscribing so you can prevent this mistake from happening again.

However, asking them a reason to unsubscribe should be without any pre-conditions.

And please – don’t hide your unsubscribe form behind a login screen; that is the worst kind of unsubscribe option. Chances are the user won’t wait for another second to mark you as spam if they see a login screen linked to an unsubscribe button.

8. Your email frequency may be too high or your sending times may not be optimal

An unaware or uninformed email strategy may be yet another reason why your email gets regularly marked as spam or you may start receiving spam complaints.

Run some A/B tests to know what are the email preferences of your audience are. It includes the frequency and the sending time for your emails. Stick to those which give you maximum engagement.

Another way to ensure an optimal email frequency is to study industry averages. For more tips on email frequency, check out Email Frequency Guide from TheSeventhSense.


The success of your email marketing campaign depends on your own campaign strategy as well as the service provider you choose to send emails from.

Of course, creating a conversion-optimized email with intriguing subject lines and engaging CTA is very important. But after spending all the effort and time in debugging the marketing issues out of your emails, you wouldn’t want the campaign to fail because of a spam neighbor on your shared IP.

Worse yet, you don’t want to discover that your sender was already blacklisted. Hence, you must actively guard your email deliverability rate.

Besides, your emails already have so much competition when they reach the users’ inbox. But if they don’t even see the inbox, they don’t even get the chance to compete.

Implementing the best email deliverability practices allows you to get out an email marketing funk by providing an enriching email experience, not to mention, it will reduce the bounce rate drastically.

How is your email deliverability rate? When did you last check email deliverability rate? What is your email sender score? What is your email reputation score? Go ahead and test email deliverability. Do you feel the need to implement any of the steps given in this article? Do let us know in comments.

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