Ugh, this drives me nuts. It's the same reason why I stopped using my Supernote Nomad for email.
I use iCloud+ email with a custom domain. With that arrangement you authenticate to Apple's servers with your iCloud "primary address", like [email protected]. Then you can send and receive email with your custom domain email address, which is the one you're actually using. But not with Supernote, or apparently Penguin Mail. My Nomad will only send mail with my @icloud.com address, even though that's only used for authentication.
So yeah, I just stopped using it altogether. That's not my address. It's not how people reach me. It's literally just a username.
I'll stick with the web UI in that case. Are you using any other clients on Mac or Linux?
Fastmail is not something I use as default, so I had to check a lot of documentation, and some of the Fastmail features are probably missing, I'll have some of these on the coming versions
- can’t choose a sender email?! This is major dealbreaker, if you have many aliases or domains.
- no favico for emails, this is also a deal breaker for me, as I used it to quickly skim and find or check new emails.
- folders orders is messed up, trying to arrange them made it worse
- trying to color a folder and it says “server doesn’t support that”
Also the UI needs more polishing overall.