Search for emails from not a particular user or subject in Apple Mail
Mail can perform Boolean searches, but only in message contents, not in headers (such as Subject, From, or Date).

When using Boolean operators, always use uppercase — AND, OR, and NOT — so Mail doesn’t search for the actual words and, or, and not. You can use a minus sign (-) as a shortcut for AND NOT, so, if you type Jack -Jill in the Search field, you’ll see a list of all the messages that contain “Jack” but not “Jill.”

UPD. I've tried with my own mails and it looks like Mail DOES sort headers too. So try to enter into search field: abc NOT whatever-you-want-to-exclude. Shall work.

More info here: https://support.apple.com/kb/PH22310?locale=en_US&amp;viewlocale=en_US