Seems, if message has multi-part structure and if one of parts were lost:
/usr/local/fido/gate/bin/runinc missing: 21 Jun 16 03:20:44 @770/3 00000 02 / 02 message <> incomplete!
Ok, there were some leftovers in the fidogate's spool. Why they appeared initially is not clear, but feel free to reopen the issue as soon as you can reproduce it.
Seems, if message has multi-part structure and if one of parts were lost: /usr/local/fido/gate/bin/runinc missing: 21 Jun 16 03:20:44 @770/3 00000 02 / 02 message <> incomplete!