One of the reasons I like email so much is because you can instantly figure out how good (or bad) it’s performing.
But you can only really do that if you’ve got some sort of measurable action.
Luckily, forcing yourself to put a measurable action into an email is a great way to ask yourself “what am I trying to achieve with this message?”
For some messages, it’s easy: you want people to donate. Or you want them to add their name to a petition. Those are easy to measure.
And then you could (should) be reporting back on how you spent their donation.
There’s a simple opportunity there: in the report back, provide a way for them to engage with you again. Provide a link for them to share their accomplishment with their friends. And put a passive donation ask in there too, because people will want their donations to achieve more of the same or continue the fight*.
It doesn’t really matter what kind of message you’re sending – if it’s a quality message, people will want to engage with you. And it’s up to you to provide that opportunity for engagement every time.
Do this a few times and you’ll quickly figure out your baselines. Then test and optimise.
*Don’t expect this to be a driver of significant income – think of it as a reward for a job well done.