I've had a personal domain for a couple of years now and I'd like to start using it for email. I've had iCloud+ so I linked it up to that, but I don't really use it that much. The #1 feature I use is the "catch-all" email address: any email sent to whatever@my.domain (replace "whatever" with any text) is routed into my inbox. This has the nice intention of easily creating filter rules based on what email I used for a website.

My gripe with using iCloud for my email is that I just am not a fan of the mail client. Because of this, I've been very reluctant to send emails with it and prefer using my personal Outlook.

I use my personal email with the Outlook client, but I link this to a Google account mostly for convenience. I feel like switching entirely over to Google Workspace would be nice, but (1): Lock in (2): I don't think Workspace supports the catch-all/many email addresses for 1 user (3): I don't like Gmail's client. Switching over to Microsoft 365 has problems 1 and 2, just not 3.

What is the best solution for running email, preferably FOSS?