Deliverability is an ever-changing concept and a vital component of every strong email marketing campaign. This blog takes a look at email deliverability and explains what you need to know.

What is deliverability?

Put simply, deliverability is the ability to get an email into the intended recipient’s inbox. It is an issue that every email marketer needs to be aware of and monitor. What is the point in spending days meticulously designing email campaigns if your intended recipient is never going to see them? Part one in this series will give a brief overview of how email actually works and what happens when an email cannot be delivered to the intended inbox.

How does an email work?

An email works in a similar way to a letter. If we think about a standard letter, it consists of two components; the envelope and the written message. The message is simply the information contained within the email. The envelope is used to distinguish where the mail should be delivered.

As an example, if we take the email address ‘’ we can see what each aspect refers to:

  • ‘Example’: this details the name of the person the email should be delivered to
  • The ‘domain’: equivalent to the country/state/city
  • ‘.com’: this equates to the postal/zip code on a letter

This information is handled by the Mail Transfer Agent (MTA), which is the email equivalent of a postman.

Undeliverable emails

Deliverability rates have been decreasing over the years. The latest studies show that around 20% of emails sent do not reach their inbox. This staggeringly high amount highlights the importance of deliverability and why every email marketer should constantly strive to improve it to ensure they get the best return on their investment. Why should you spend resources on email marketing when there is no guarantee that the intended recipient will receive them?

One key factor when trying to improve deliverability is to action any bounce messages you receive. A bounce is received when an email fails to be delivered to its intended mailbox; the equivalent of a ‘return to sender’ note from the postman.

Types of bounces

There are two types of bounces; hard and soft. A hard bounce is a permanent failure to deliver and a resend should not be attempted until this issue is addressed. Common reasons for hard bounces include an incorrect email address or an invalid domain.

A soft bounce is a temporary failure to deliver. Most email servers will continue to try to deliver for a few days. Some common reasons for soft bounces include the recipient’s inbox being full or a server being offline.

 Industry standards indicate that your overall hard bounce rate should be below 5%. Hard bounce rates above 5% run the risk of being blocked by some email servers.

With deliverability being a vital component of any strong email marketing, it is important to take the necessary steps to ensure your email reaches the recipient. In part two of our piece on deliverability, Concep's Gareth gives his top tips on improving yours.

Now that we are aware of how important deliverability is, the next step is to take measures to improve it.  One of the biggest ways to improve your deliverability is to develop your sender reputation. This is a score given by your Internet Service Provider which tells mailboxes how trustworthy your IP address is as a sender i.e. the likelihood that you are a spammer. It is rated on a scale of 0-100 with 0 being the worst and 100 being the best. Ideally, you want your score to be above 80. If you are using Concep Send, your sender reputation will be 97-100. 

There are a number of factors which can negatively affect your sender reputation, including sending to known undeliverable email addresses and sending emails with lots of spam heavy content.  I have included some useful tips below that you can use to improve your sender score and your deliverability.

Action Bounces

First and foremost, it is vital to action any bounce back messages you receive. Invalid or ‘dead’ email addresses must be deleted from your contact list. Many spammers use the ‘pray and spray’ method, sending out a huge number of emails hoping that someone will buy the product when they hit a valid account. Spammers do not stick around to clean their list, hence why it is vital that you clean yours to avoid being labelled as a spammer by recipient email inboxes.

Avoid spam filters

You should take every possible measure to avoid being caught in the spam filter of your recipients.  Avoid words related to money; such as ‘discount’, ‘free’ or ‘limited offer’ in your subject line.

Additionally, you should ensure you have a good text to image ratio. Too many images can cause your emails to be delivered straight to the spam folder. Poorly coded HTML emails can also fall victim to spam traps so make sure your code is clean, with no open or unnecessary tags.

Help your contacts to help you

Consistently unengaged recipients can lead to hard bounces. Including a double opt in for clients will ensure that recipients will only receive your emails if they have signed up and confirmed. The addition of a preference centre, where recipients can identify particular areas they are interested in, will improve your email open and engagement rates; which will have a direct positive effect on your deliverability. If a recipient is consistently not engaging with your emails, consider the use of a re-engagement campaign to try to ‘reach-out’ to the recipient in an effort to get them to engage more with your emails.

Additionally, make your unsubscribe links obvious to further ensure that contacts who are no longer engaged will no longer receive your emails.

 Follow these tips and you will be well on your way to improving deliverability for your email marketing.