Clicked on a folder in Thunderbird and got this in the log: Nov 6 22:49:11 one dovecot: imap-login: Login: ts at dreamcoder.dk [10.24.0.1] Nov 6 22:49:11 one dovecot: IMAP(ts at dreamcoder.dk): Corrupted index cache file dreamcoder.dk/ts/Maildir/.INBOX.Mailing Lists.bugzilla/dovecot.index.cache: indexid changed Nov 6 22:49:11 one dovecot: IMAP(ts at dreamcoder.dk): file mail-cache-fields.c: line 338 (mail_cache_header_fields_get): assertion failed: (buffer_get_used_size(dest) == sizeof(hdr) + (sizeof(uint32_t)*2 + 2) * hdr.fields_count) Nov 6 22:49:11 one dovecot: child 469 (imap) killed with signal 6 -- Tom