I still use Thunderbird but on my Linux system that I just set up I would like to try something else.

Some options appear in this thread: https://www.reddit.com/r/software/comments/17r3twi/best_wind...

If you’re doing a new install and are generally fine with Thunderbird, Betterbird is a good option. It has additional good stuff that Thunderbird is lacking or took longer to get implemented/fixed.

What I don’t like about Thunderbird is that the profiles aren’t portable. It seems like every Thunderbird install is its own unique mess. I’d love to find something that allowed me to move the same configuration around between computers and platforms. I’m not sure if that exists.

I like how Thunderbird has the ability to handle mail, calendar, and contacts, but the implementation especially for calendar leaves a lot to be desired.

My favorite clients are Apple Mail/Calendar for their simplicity and being local-first clients but I’m using macOS less and less these days.

The “new outlook” that’s offered by Microsoft to consumers for free seems to be creepy and syncs your emails to Microsoft servers even if you’re using a third party client.

I’d also say you only need a truly local client if you have multiple email addresses. If you have just one email, let’s say you’re with FastMail or something, their web mail and mobile/desktop apps are great.