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Email subject line length

Posted by Michael Bloch in web marketing (Tuesday June 3, 2008 )

40 characters, 50, 60.. or more? Just how many characters should you use in email subject lines for marketing communications?

The CEO of Alchemy Worx believes that open rates improve when subject lines are in the 50 character range or 80 character, depending on the type of communication – but oddly enough, they bomb a little when around the 60 or 70 mark.

His thoughts were formed after a study of 250 million messages sent over 24 months and 660 different subject lines. The 50 character subject line appears best for special offer promotions, whereas the 80 character range is more suited to newsletters.

I tend to agree with him on the principle of a longer subject line for newsletters. So many newsletters I get only mention one item contained within in the subject line and if I’m in a hurry, unless that one item is of interest, I tend to gloss over it. If a newsletter subject line mentions several topics, there’s a better chance I’ll open the email.

For example

News – BigCorp announces merger < - no interest vs. Free pizza, PPC stats, BigCorp merger and more <- very interested As we don't know exactly what will trigger the interest of all individuals on our lists, mentioning a couple of items in the subject line gives us a better chance of stirring curiosity to a wider group. Also putting the item you feel to be of the most interest up front is a good idea as people set their subject line column in their email software to varying widths - it's for that reason I recommend a subject line of 50 characters maximum (or at least the "meat" of it). As with any "best practice", the one that's most effective is the one that works for you. You'll see conflicting ideas as to the perfect subject line length, so experiment with your own lists a little. You can read more of Dela Quists subject line observations here and pick up some more subject line tips here.


Email marketing software
Email delivery issues
Gauging email open rates


1 comment for Email subject line length
  1. Hi thought you might be interested to hear that this story was based on a conversation I had at the email insider summit about an incomplete white paper I was working on. The research is now complete and if anything the results are even more conclusive than I had hoped for!

    I run Alchemy Worx – a digital marketing agency with a 100% focus on email, and our findings are based on analysing over 600 subject lines and 200 million email messages and believe that this research disproves (PDA’s aside) the widely held view that short email subject lines are better.

    We discovered that although subject lines with 50 characters or less make more people open the email – the traditional view – they are less likely to then go on and click on content or offers within the message. The study found that the click-to-open rates start to be optimised when the subject line is over 70 characters in length and continue to rise until well beyond 100 characters.

    This is true for both the number of characters and the word count. The more words there were in the subject line, the better the click-to-open rate.

    One of the most common questions I am asked at conferences is what subject lines work best, so I am delighted to discover this rule of thumb.
    In the last eight years of working on our clients email marketing programmes we amassed plenty of circumstantial evidence that suggested longer subject lines could be as, if not more effective than shorter ones, so we commissioned this research to find out once and for all.

    In summary our findings show that:
    – Short subject lines less than 50 characters long or containing less than 6 words optimise open rates

    – Long subject lines – over 70 characters or 10 words optimise both click and click-to open rates

    We were also surprised to identify a “dead” zone!

    – Subject lines of between 60 and 70 characters (6-10 words), optimise neither the open rate or click to open rates.”

    The white paper containing full results and analysis is now available as a free download

    Comment by Dela Quist — July 8, 2008 @ 5:33 pm

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