The one “default” textual content alternative on macOS 15.3.2 is “omw” so what you describe is not one thing I can reproduce.
- Mail app solely triggers a particular habits in three fields for me (to:, cc:, bcc: ) and the primary @ begins a search in your contacts database.
- Anyplace else within the app, nothing occurs except your textual content alternative database has a success.
It is attainable however unlikely your textual content alternative database is corrupt and you’ve got an entry that you do not see in system settings. It is extra doubtless your contact database has an entry that makes the programmed lookup select your e mail for @@.
You may check this simply by making a brand new person account in your Mac, logging out of the present person and solely organising the mail app when you full all of the onboarding steps. I might not signal into your Apple Account wherever for those who can keep away from that and have a unique e mail you may check with that is not iCloud synced.
Then you may check @@ for alternative in a number of locations and return to your major account and validate what you might be seeing. Even attempting to set @@ to switch to @@ does not stop the primary @ from trying up contacts in Mail.app so I believe that you must select a unique mail app if that is one thing you may’t be taught to handle. I did not see any approach to stop this lookup in settings or some documented workaround.
