Hope you're doing great! You all have heard about different tests, including the popular one A/B test. I believe some of you tried it. Whether you are familiar with tests or not you probably know that's it's kind of a hard for newbie to choose what to test. I faced this problem when my friend asked me what are the key elements of an email campaign that should be tested. Here is the list I advised him, hope you find it helpful!
Subject lines. It's good to test all you can here - from words to tone. It's really amazing how few words or symbols or something else can double or triple your open rates.
From lines. Test company names, or people's names as a From-name. Also test female and male names, full company name or the brand name, etc.
Time of delivery. There are best times to send your emails, but as you know there's always an exception. Maybe you have a special niche and people in this niche are more active on Monday, or Friday for example. No one knows!
Call to action. Oh, so many things to test here - type, size, color, placement, text and many other elements of a call-2-action. You should define first what type converts best for your list - regular links or buttons/images.
Email length. Some think that short messages converts best (I am on this side too), however, some think that your letter should extremely detailed and informational. Again, test it!
Don't forget to track and analyze changes, Atomic Email Tracker is best for this - both online and stand-alone versions.