Per MarketingSherpa, the open rate for email is not what it seems.

fact, the stalwart of email marketing metrics is flawed
because image blocking reduces the ability to measure an
open rate. So, it’s limited in its usefulness for email

This is why email marketers should think twice before making
changes to their strategies and programs based solely on
open rates.

However, you still need to give more attention to writing relevant copy, sub segmentation of your lists and more.