Two particularly important groups for our purposes are customers with a one-time purchase and customers who have purchased multiple times. A customer is sometimes not considered to be loyal or repeat customer until they have purchased two to five times, in which case the single purchase segment is more akin to a warm prospect than a loyal customer.

This A/B test indicates that engagement is one problem, but your subject lines are an even bigger problem—and one you can solve right away. CTR rates are understandably lower among the less-engaged group, but you saw engagement increase with a punchier subject line, so there is room to improve CTR among cold leads. CTR rates are higher in the more engaged group, but with a better subject line, this rate could go through the roof.

Then, send promotional emails through Auto Responder to your list. Your subscribers will click just 1 same link (main rotator URL), and the rotator will display all the different links to different visitors. Then you can monitor how many links being delivered inside the rotator and stop it when done (You can set it to stop automatically when clicks delivered).
Part of the problem is that people are confused about the difference between ‘strategy' and ‘tactics'. It's essential not to get these two confused. They are related – tactics are a vital part of what makes a strategy work – but they’re not the "be all and end all." Too many people neglect a full and comprehensive strategy in favour of a bunch of loosely-connected tactics. So, to recap: