The red line follows the thin line that should form a part of the 'm'...there should not be anything in the area of the green oval.

I think the cancel has created two blobs - on the 'm' and the 'a' - that make the letters look like they have extra serifs.
Either that, or the stamp is not authentic.
I'm expecting to receive the 15-volume German Philatelic Society Forgery Manual this week, and will check for any candidates that match yours.