Debug output:
May 6 11:23:42 qemu-sid dovecot: master: Dovecot v2.2.16 starting up for imap (core dumps disabled) May 6 11:24:06 qemu-sid dovecot: imap-login: Login: user=<bluser>, method=PLAIN, rip=192.168.122.8, lip=192.168.122.8, mpid=441, secured, session=<HtpSW2YVaQDAqHoI> May 6 11:24:06 qemu-sid dovecot: imap(bluser): Debug: Loading modules from directory: /usr/lib/dovecot/modules May 6 11:24:06 qemu-sid dovecot: imap(bluser): Debug: Module loaded: /usr/lib/dovecot/modules/lib15_notify_plugin.so May 6 11:24:06 qemu-sid dovecot: imap(bluser): Debug: Module loaded: /usr/lib/dovecot/modules/lib20_mail_log_plugin.so May 6 11:24:06 qemu-sid dovecot: imap(bluser): Debug: Effective uid=1000, gid=1000, home=/home/bluser May 6 11:24:06 qemu-sid dovecot: imap(bluser): Debug: Namespace inbox: type=private, prefix=, sep=, inbox=yes, hidden=no, list=yes, subscriptions=yes location=mbox:~/mail:INBOX=/var/mail/bluser May 6 11:24:06 qemu-sid dovecot: imap(bluser): Debug: fs: root=/home/bluser/mail, index=, indexpvt=, control=, inbox=/var/mail/bluser, alt= May 6 11:24:06 qemu-sid dovecot: imap(bluser): delete: box=inbox-b, uid=15988, msgid=20150113080229.634B31FE0F@example.com, size=166 May 6 11:24:06 qemu-sid dovecot: imap(bluser): expunge: box=inbox-b, uid=15988, msgid=20150113080229.634B31FE0F@example.com, size=166 May 6 11:24:06 qemu-sid dovecot: imap(bluser): Error: Sync failed for mbox file /home/bluser/mail/inbox-b: seq=13 uid=15999 uid_broken=0 originally needed 0 bytes, now needs 23 bytes May 6 11:24:06 qemu-sid dovecot: imap(bluser): delete: box=inbox-b, uid=15989, msgid=20150113080252.84E723FB47@example.com, size=238 May 6 11:24:06 qemu-sid dovecot: imap(bluser): expunge: box=inbox-b, uid=15989, msgid=20150113080252.84E723FB47@example.com, size=238 May 6 11:24:06 qemu-sid dovecot: imap(bluser): delete: box=inbox-b, uid=15990, msgid=20150113080253.3E89D5F8B1@example.com, size=238 May 6 11:24:06 qemu-sid dovecot: imap(bluser): expunge: box=inbox-b, uid=15990, msgid=20150113080253.3E89D5F8B1@example.com, size=238 May 6 11:24:06 qemu-sid dovecot: imap(bluser): delete: box=inbox-b, uid=15991, msgid=20150113080256.702551FD75@example.com, size=238 May 6 11:24:06 qemu-sid dovecot: imap(bluser): expunge: box=inbox-b, uid=15991, msgid=20150113080256.702551FD75@example.com, size=238 May 6 11:24:06 qemu-sid dovecot: imap(bluser): delete: box=inbox-b, uid=15992, msgid=20150113081736.928595F8B1@example.com, size=238 May 6 11:24:06 qemu-sid dovecot: imap(bluser): expunge: box=inbox-b, uid=15992, msgid=20150113081736.928595F8B1@example.com, size=238 May 6 11:24:06 qemu-sid dovecot: imap(bluser): delete: box=inbox-b, uid=15993, msgid=20150113090223.890703FBC5@example.com, size=166 May 6 11:24:06 qemu-sid dovecot: imap(bluser): expunge: box=inbox-b, uid=15993, msgid=20150113090223.890703FBC5@example.com, size=166 May 6 11:24:06 qemu-sid dovecot: imap(bluser): delete: box=inbox-b, uid=15994, msgid=20150113090225.EA3BF1FDD0@example.com, size=166 May 6 11:24:06 qemu-sid dovecot: imap(bluser): expunge: box=inbox-b, uid=15994, msgid=20150113090225.EA3BF1FDD0@example.com, size=166 May 6 11:24:06 qemu-sid dovecot: imap(bluser): delete: box=inbox-b, uid=15995, msgid=20150113090235.947643FB11@example.com, size=238 May 6 11:24:06 qemu-sid dovecot: imap(bluser): expunge: box=inbox-b, uid=15995, msgid=20150113090235.947643FB11@example.com, size=238 May 6 11:24:06 qemu-sid dovecot: imap(bluser): delete: box=inbox-b, uid=15996, msgid=20150113090252.ACE3D5F8B1@example.com, size=238 May 6 11:24:06 qemu-sid dovecot: imap(bluser): expunge: box=inbox-b, uid=15996, msgid=20150113090252.ACE3D5F8B1@example.com, size=238 May 6 11:24:06 qemu-sid dovecot: imap(bluser): delete: box=inbox-b, uid=15997, msgid=20150113090252.F11061FDAE@example.com, size=238 May 6 11:24:06 qemu-sid dovecot: imap(bluser): expunge: box=inbox-b, uid=15997, msgid=20150113090252.F11061FDAE@example.com, size=238 May 6 11:24:06 qemu-sid dovecot: imap(bluser): delete: box=inbox-b, uid=15998, msgid=20150113091737.92CD33FC52@example.com, size=238 May 6 11:24:06 qemu-sid dovecot: imap(bluser): expunge: box=inbox-b, uid=15998, msgid=20150113091737.92CD33FC52@example.com, size=238 May 6 11:24:06 qemu-sid dovecot: imap(bluser): Disconnected: Logged out in=1364 out=6726