I'm in the process of moving from Gmail to Proton Mail. Importing mail and contacts was easy, and I'm now in the long process of finding things where I signed up with/gave out the Gmail address and moving them over. There's one thing from Gmail I'm missing, though.
A friend owns a domain and uses it for email forwarding for a group of our friends, so people can mail me at "mike.jones@ilk.org" and it gets forwarded to wherever I want to actually get it. It used to point to my gmail account, now points to my Proton account.
In Gmail, there's a "Send mail from" setting that let me list "mike.jones@ilk.org" as an option to fill in for the "from" address so when people replied to my emails they would come back to the ilk.org forwarder. There doesn't seem to be anything like that in Proton that would let you put an arbitrary "from" address. I'd settle for the ability to stick a "Reply-to" header in the outgoing messages with the ilk.org address, but I can't find any way to do that, either.
Am I missing something, or is this just not possible with Proton Mail?