So, in light of the discrepancies highlighted above, what can you do to ensure that email headlines generate the most clicks?
Something called front-loading. You load the most important words for your subject into the beginning, and it's the first option.
The next option is to segment your list. You can potentially segment your list into various groups, including basing lists on which email platform the reader uses.
Then, you can create a different headline for one email newsletter for each platform: Yahoo, Outlook, Gmail, GoDaddy.
The problem posed with this solution is that you may not be able to know what platform someone is in, if the email address is linked to a website besides one listed above.
So, it may be best to stick with front-loading and using shorter headlines for email recipients