In Mail v16.0 on MacOS Sonoma v14.5, I'm finding the "Remove Attachments" option is disabled on any message that I've sent. I can still remove attachments on incoming email.
(It took a while to find a fix so I'm answering my own question below.)
If your mailbox has a lot of messages in it and you don't want to rebuild the whole thing for the sake of just a couple of messages, you can create a new empty folder, move the message(s) to that one, rebuild that folder, remove the attachments, and then move the messages back to the folder they came from.
If your mailbox has a lot of messages in it and you don't want to rebuild the whole thing for the sake of just a couple of messages, you can create a new empty folder, move the message(s) to that one, rebuild that folder, remove the attachments, and then move the messages back to the folder they came from.
How to Fix Apple Mail when "Remove Attachments" is disabled?
