Tru Pheenix writes:

posftconf output: https://gist.github.com/anonymous/7318863 doveconf output: https://gist.github.com/anonymous/7318896 tail -f /var/log/mail.* output (when receiving mail): https://gist.github.com/anonymous/7318945

Unless these are exceeding long, you probably should inline the contents to save people from having to jump around to get the information to help you. It will also properly archive the context to the solution.

From your logs, it appears your mail system does not know what user is mapped to "someone@mydomain.com":

Nov  5 13:21:06 localhost postfix/local[11185]: 5716D8007B: to=<someone@mydomain.com>, relay=local, delay=0.59, delays=0.57/0.01/0/0.01, dsn=5.1.1, status=bounced (unknown user: "someone")

I don't know whether this message is produced by postfix or by dovecot, but one thing I did notice is that your postfix configuration

mailbox_command = /usr/lib/dovecot/deliver -c /etc/dovecot/conf.d/01-mail-stack-delivery.conf -m "${EXTENSION}"

has upper-case "EXTENSION", whereas the Dovecot wiki uses lower case:

http://wiki2.dovecot.org/LDA/Postfix

If that's not it, maybe it's your SQL. You can also ask dovecot to look up user "somebody" and debug your way from there:

doveadm user somebody

Joseph Tam jtam.home@gmail.com