This is in follow-up to https://dovecot.org/pipermail/dovecot/2017-December/110443.html I had mail_plugins = "zlib", but zlib_save wasn't set (my mailboxes were not compressed). It seems that when the zlib plugin is enabled, but zlib_save isn't set, the zlib plugin aborts on a regular basis---on a single-user system, I was seeing it about 150 times a day. Panic: file ostream-zlib.c: line 36 (o_stream_zlib_close): assertion failed: (zstream->ostream.finished || zstream->ostream.ostream.stream_errno != 0) Fatal: master: service(imap): child 80128 killed with signal 6 (core not dumped - set service imap { drop_priv_before_exec=yes }) Removing the (unused) zlib plugin made the errors disappear, at least. # Adam -- Adam Weinberger adamw at adamw.org http://www.adamw.org