Because it's only INSERT not SELECT nor DELETE? Maybe you meant IMAP which does have APPEND <https://www.rfc-editor.org/rfc/rfc3501.html#section-6.3.11> to insert a new message into a folder, and a bazillion SELECT options, plus of course DELETE
I still would call that crazy, because of the mental tax of explaining to every new employee "wait, you're using IMAP for what?" but if it works for you, then great
People will call me crazy but why not SMTP for message queueing?
Because it's only INSERT not SELECT nor DELETE? Maybe you meant IMAP which does have APPEND <https://www.rfc-editor.org/rfc/rfc3501.html#section-6.3.11> to insert a new message into a folder, and a bazillion SELECT options, plus of course DELETE
I still would call that crazy, because of the mental tax of explaining to every new employee "wait, you're using IMAP for what?" but if it works for you, then great