If mehitabel is interrupted or (heaven forbid) crashes during its operation, you should be able to recover your messages rather easily:
1 — Rename the MESSAGES, MSGHDR and MSGTXT files to temporary names (such as MESSAGES.temp, MSGHDR.temp and MSGTXT.temp).
2 — Rename the MESSAGES.Bak, MSGHDR.Bak and MSGTXT.Bak files to MESSAGES, MSGHDR and MSGTXT and put them in the correct folders.
3 — Run Host to verify that all is well.
If everything works, you can toss the three .Temp files. If not, then your message files suffered some calamity before mehitabel got to them. Try running mehitabel on these three files again — mehit filters out most kinds of “bad” message headers, and this filtering can often recover trashed message files.