The exmh MUA uses app-text/antiword to render word files inline, if antiword is installed. I suggest a USE flag is added to exmh. Note: exmh always probes at runtime if antiword is on the PATH, USE-flagged or not. If an USE flag is added to exmh, it could NOT be used to make exmh NOT use an installed antiword. I'm not sure if that's a real prblem, though. Reproducible: Always
The mail-client/exmh package was removed from the tree a couple weeks ago, marking as maintainer-wanted.
exmh no longer is in the tree, so little we can fix here, sorry