MailMate does this with a setting in the account called “Address Pattern”.
When replying to a message, MailMate automatically tries to use the email address for which the original message was sent. This does not require the address to be explicitly declared in the settings, but it does require an “Address Pattern” as described below.
not sure this counts, I am using Fmail Mac wrapper , I have numerous masked email addresses. I believe that by default fastmail will reply to any email using the “to:” address. However, to send email without a reply using the masked email address, I have to set up some as Sending Identities.
These settings are from fastmail web interface or you can change this from any Mac app for Fastmail , I think
I also use Fastmate as my desktop wrapper of choice. It’s great and my default for composing new messages, but I’m longing for something more native
Something that doesn’t require adding identities first (like Apple Mail), but is fully comfortable with wildcard addresses
I slapped together an AppleScript that adds a new identity to Apple Mail when I hit CMD-R (through KM) but it’s a bit ghetto and doesn’t work reliably. I looked into the Mail extension API as well but it’s very limited and doesn’t allow these kind of deep interactions. Would need to be a pretty hacky solution to bake this into Apple Mail directly, though not impossible I think
reviving this ‘old’ discussion. @ryanjamurphy , do you have to add the alias into Airmail beforehand? I have hundreds of masked email in Fastmail , so adding them prior is not practical. I tried to reply to an email sent to one of masked email addresses but Airmail default to one of my alias email address that I entered into Airmail. Is there a setting that I have missed or Airmail only works with email aliases not masked email addresses?