Thanks for your report.
The relevant message is
=
Errors found in /tmp/dpkg-error/506797/DpkgTerminalLog.gz
Setting up dovecot-postfix (1:1.1.11-0ubuntu11) ...
* Restarting IMAP/POP3 mail server dovecot
Info: If you have trouble with authentication failures,
enable auth_debug setting. See
** Attachment added: AptOrdering.txt
http://launchpadlibrarian.net/37837592/AptOrdering.txt
** Attachment added: Dependencies.txt
http://launchpadlibrarian.net/37837593/Dependencies.txt
** Attachment added: Dmesg.txt
http://launchpadlibrarian.net/37837594/Dmesg.txt
** Attachment