In email marketing you can try out several techniques and styles, in an easy and cheap way.
For instance, do you use a mysterious subject line to tickle curiosity rather than make a clear offer?
Try both options and you’ll know which works best.
The most important parameters to test in email marketing are the subject line, your offering, the position of your visuals and your content.
But be sure never to test more than one parameter at a time, otherwise your results will be dubious.
Conclusion: To optimise your email campaigns, test what works best and learn more about the behaviour and expectations of your recipients.