For experienced email marketers this is an obvious tip. There is a lot of testing to do in email marketing to see what works best for both, you and your customer in general.
Testing helps you to find out what type of content works best, what’s the best day to send an email and much more.
However, besides these more general tests, that provide you tactical insights on a medium to long term, you also need to test your emails prior to sending them.
The relevance of an email is an extremely important factor that contributes to the succeeding or not succeeding of an email marketing campaign.
Email subscribers have specific expectations when they confirm their registration. Make sure to communicate the subject, topics and frequency on the registration form, so every receiver knows what to expect.
Offering different frequency options can help too since frequency is one of the main reasons why people unsubscribe. When someone subscribes to your email list you should immediately gather his preferences from the very start of the subscription process.