Applying Atbash: t (20) ↔ g (7) h (8) ↔ s (19) m (13) ↔ n (14) y (25) ↔ b (2) l (12) ↔ o (15)
It looks like the subject line you provided——is likely a cipher or typo-transformed text. thmyl ttbyq synmana brw
One common possibility is that each word is a reversed version of an English word or name. Applying Atbash: t (20) ↔ g (7) h
→ (first word)
Request the sender to provide the plaintext or the cipher method used. thmyl ttbyq synmana brw