amavis не пропускает письма с вложениями, если имя файла-вложения на русском языке.
Mar 14 13:18:06 avangate postfix/qmgr[6429]: A531233B0B6: from=<les@avangard.dn.ua>, size=36428, nrcpt=1 (queue active)
Mar 14 13:18:06 avangate amavis[19698]: (19698-18) (!!)TROUBLE in check_mail: mime_decode-1 FAILED: MIME::Words: unexpected case:\n(\x{041d}\x{0430}\x{0447}\x{0430}\x{043b}\x{044c}\x{043d}\x{0438}\x{043a}\x{0443} \x{0412}\x{043e}\x{0440}\x{043e}\x{0448}\350\353\356\342\361\352\356\343\356 \320\316\323\314\302\304.doc) pos 0\n\tPlease alert developer.
Mar 14 13:18:06 avangate amavis[19698]: (19698-18) (!)PRESERVING EVIDENCE in /var/spool/amavis/tmp/amavis-20110314T125750-19698
Mar 14 13:18:06 avangate postfix/smtp[21561]: A531233B0B6: to=<exeraser@gmail.com>, relay=127.0.0.1[127.0.0.1]:10024, delay=126357, delays=126357/0.01/0/0.06, dsn=4.5.0, status=deferred (host 127.0.0.1[127.0.0.1] said: 451-4.5.0 Error in processing, id=19698-18, mime_decode-1 FAILED: MIME::Words: unexpected case: 451-4.5.0 (\x{041d}\x{0430}\x{0447}\x{0430}\x{043b}\x{044c}\x{043d}\x{0438}\x{043a}\x{0443} \x{0412}\x{043e}\x{0440}\x{043e}\x{0448}\350\353\356\342\361\352\356\343\356 \320\316\323\314\302\304.doc) pos 0 451 4.5.0 \tPlease alert developer. (in reply to end of DATA command)) 

Временное решение: http://forum.lissyara.su/viewtopic.php?f=20&t=31360 

Обновите версию perl-MIME-tools