Are your emails failing to deliver?

For some email marketing systems, it's called "delivered", some know it as "delivery rate" or perhaps your email service provider (or ESP) calls it something slightly different?

Whatever it is called, most of us have always assumed it means what it says - we sent 100 emails and the report shows a 98% "delivered" rate, so 98 got into the recipient inboxes, right?


This metric, which all ESP systems will offer us, is more like "Gone but not come back" rate. That's to say that of those 100 emails sent, the system was notified of any bounce backs but otherwise it is assuming the rest got through to inboxes and are waiting to be opened.

Unfortunately, with the vast number of spammers still out there (and therefore a large array of spam blockers and checkers between your email being sent and the recipient's inbox), the true "delivered" rate is likely to be lower than that.

In fact, it is somewhere between that and the next metric you see, the open rate.

This is not some great conspiracy by all the ESPs out there, to hoodwink us, it's just always been an indicator rather than an exact measure. As such we should learn from this and make time to ensure we minimise the risk of being caught or filtered by those various email checking systems out there.

The most common reasons why your emails might be stopped before getting to the inbox:

  1. BODY: HTML has a low ratio of text to image area
  2. BODY: Message only has text/HTML MIME parts
  3. BODY: HTML has a low ratio of text to image area
  4. BODY: HTML and text parts are different
  5. Subject is all capitals
  6. BODY: HTML and text parts are different
  7. BODY: HTML: images with 2400-2800 bytes of words
  8. BODY: HTML: images with 2000-2400 bytes of words
  9. BODY: HTML: images with 1200-1600 bytes of words
  10. BODY: HTML: images with 1600-2000 bytes of words

(Thanks to our friends MailChimp for this list.)

Alas, email marketing is a blend of art and science and so learning and remedying such issues is vital to the success of every email marketer out there.

Happily, this is just one of the many topics that we discuss and work through during my IDM Email Marketing: Strategy and Tactics Course. Learn how to improve the delivery rate of your emails plus much, much more. Take a look at the full syllabus here.

Did you find this blog useful?

At the IDM we are passionate about educating marketers and providing resources to help advance your career.

If you are interested in enhancing your CV and upskilling, browse through our wider range of marketing courses and qualifications; from one-day short courses to post-graduate diplomas.

Our learning and development team will be happy to advise based on your needs and requirements.

Back to blogs
Contact Us