Improving Email Deliverability

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Before you start looking to improve your clicks and conversions from emails, you’ll need to make sure that your emails are actually getting into your contacts inbox – and once they are, that they are being opened, rather than deleted, or worse - being flagged as spam.


Where did your data come from?

First of all, where did these email addresses come from? Did these people actually opt in to receive emails from you? Or, did you look for an easier way to grow your mailing list?


Buying a list from a data house or harvesting emails

It can be tempting to buy a list from a data house, but even some of the better and more expensive ones will never yield results in the same way a warm list will.

As well as purchasing and renting lists, another way to build a database is through harvesting emails. Just one form of email harvesting involves visiting places such as forums relevant to your sector, and scraping email addresses to put into your lists.


Why your email may never get to the inbox

The majority of data houses will sell you crappy, ancient email addresses. They’ll tell you that the data is cleaned regularly, and that the deliverability will be great.

Shocker - it most likely won’t be.

I predicted that the results of a quality analysis that I ran on a list of over 2,200 email addresses would return approximately 75% of the email addresses as being rhubarb, full of dead domains, spam emails, and throwaway emails.

After doing three sends to the data, I wasn’t far off; just 24% of the list could be delivered to. Even then, the quality of the list that remained was awful, with a huge number of unsubscribes, and very few opens.

Harvesting emails is likely to give you similar results!

Why nobody will open your emails

If it even makes it to the contacts inbox, you don’t stand much of a chance.

It’s the same as cold calling; think about how you feel when you get an annoying PPI call (even when you’ve never had a loan or credit card). You’ve never heard of this company, and you don’t require their services, so why the hell would you care?

Even if it makes it to the inbox through spam filters, chances are it will still be deleted, or worse - flagged as spam.

What impact does this have?

Aside from annoying people that do receive your email, which can damage your brand’s reputation, sending to crappy lists can also result in damage to your sender reputation with ISPs, resulting in your IP or domain (or both) being blacklisted (use Sender Score to check if you’ve been flagged as a spammer). This will result in moving to a new IP and faffing about with changing domains – not great if you are a high volume or frequent sender.

If you are sending to a decent list with good historic deliverability alongside a crappy list from the same IP/domain, you also run the risk of all your emails ending up in the spam folder – and it may take a few sends before you even realise it’s happened.

In addition to this, ISPs will ‘plant’ email addresses that will trigger spam filters. There are two main types:

The honey pot, which involves creating email addresses and placing them in locations where they may be harvested. As soon as one (or many) of these email addresses are sent to, the ISP knows that you were naughty, and flags you as a spammer.

The spam trap reactivates email addresses that have been abandoned or closed. All emails sent to these accounts will be accepted for the sole purpose of monitoring whether as a marketer you are keeping your data up to date.

Typically these accounts are inactive for a long period, and anyone mailing to the list frequently would have had sufficient time to receive bounce notifications and remove the email address from mailing lists.

So, in a nutshell, don’t buy or rent lists, and don’t harvest emails. It’s a pretty bad idea.

How good is the data you’ve got?

So, if you have a list that is opted in, but it’s still ending up in the spam, what else could be wrong with the data?

A few things to consider would be how often you clean your lists, and how you segment them. All contacts are not created equal, so if you have a huge list, but one that is full of contacts that subscribed many moons ago who have never, ever, ever, opened an email from you, mixed in with contacts that open and click your emails on a regular basis, this could be damaging your overall send reputation through poor engagement metrics.


Segmenting your data based on past performance

Take a look through your contacts. Over a 3 month period, how many of these contacts have never even opened an email from you?

These contacts are clearly not engaged, but rather than disregarding these contacts altogether, why not move them into a new list to target with a different campaign to win them back? If, after that, they still don’t love you, maybe it’s time to consider leaving them alone?

You can segment as much as you like. This means you could end up with a lot of lists, but it will be much easier to tailor content to each audience based on their behaviour.

The Super Awesome
Contacts who will always open, click and go on to convert

The Pretty Awesome
Contacts that will always open and sometimes click

The Undecided
Contacts who open but click infrequently

The Mailbox Skimmers
Contacts who open but never take further action


Could content be the problem?

If the quality of your lists isn’t the issue, then it could be the content of your emails letting you down.

If you are using terms deemed as ‘spammy’ in the content of your emails, or are repeating the same campaign message over and over, or if the emails themselves are poorly designed with a large image to text ratio; you could end up in Spamsville.


Subject Lines and Content

Poorly written subject lines can sometimes result in your email being put into spam by ISPs, though this alone is unlikely to be causing too much of an issue.

To give you a few examples of subject line content that may trigger spam filters:


-          Excessive use of punctuation!!!!!!!!!!!!!!!!!!

-          Trigger words and phrases, such as ‘no fee’, ‘cash’, ‘free’, ‘limited time’ etc

Sometimes, you can’t get away from using these words. I mean, if you have an offer promoting free delivery, you kinda have to use the word free. And the vast majority of emails containing spam trigger words and phrases in the subject line will end up in the inbox, providing the senders’ reputation is alright.

As long as you don’t go totally nuts with repeating the message throughout the email too, you are more than likely going to be OK.

To make sure that your emails are going to be opened, take time to think about writing one that will grab attention, and gives a clear indication of what the email content is all about. There is no perfect formula for a subject line – it’s all about testing what works, and what doesn’t, over time.

Emails that are exclusively or heavily made up of images may also end up in the spam folder; again, this is not a major issue if your data and sending reputation is good. If it’s not, you may want to consider testing some new templates that include more text.

Take time to write the content in your emails, and try not to repeat the same messages too often. If a contact is getting emails twice a week offering discounts on the same products time and time again, it won’t be long before they get bored of hearing from you!

Other things to consider

Looking at data quality and content are good places to start if you’re experiencing deliverability issues.

There are a number of other factors you may want to check out too:

Consistency in who the email is being sent from

Do you always use the same sent from address? Is there consistency in the domain it is being sent from, and does your brand name always display in the same way?


Make sure your sending domain is authenticated by ensuring SPF and DKIM is set up correctly.

Delegate a Subdomain

Again, to show you are a trusted sender, delegate a subdomain using a CNAME record. As an example, the domain could have the subdomain to use exclusively for sending emails, and the from address could then be or


Check for broken links, and if you are linking to creative used in your emails, make sure the file locations where the images are hosted all match up with the sending domain too.

Shared IP Badness

It may not be you. If you are sharing an IP, one bad egg may be damaging the reputation of the IP by spamming.

Legal Requirements

An unsubscribe link is a legal requirement under the CAN-SPAM Act, so make sure it’s clearly displayed. In addition, you should also include company information, with your company registered name, number, place of registration and office address.

So, go and give your email database a health check - focus on the warm lists, double check for content spam triggers and make sure your sender account is in tip top condition, with no bad IP baggage!

For more information on improving email deliverability, speak to a member of the High Position team today.


One thought on “Improving Email Deliverability

  1. Nice post Vic! Love your suggestion on segmenting lists based on previous performance. I think all to often people fall into the trap of being solely focused on expanding their email list and forget the important job of house keeping and refining what you already have.

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