dovecot unix    -       n       n       -       -      pipe
    flags=DRh user=... -f ${sender} -d ${user}@${domain} -m ${extension}

Remove the last "-m ${extension}", then save and restart / reload postfix.

I have the default recipient delimiter set up and its working fine (that is, anything addressed to myemail+thing@mydomain.com goes to the "thing" directory in the "myemail@mydomain.com" mailbox). What I would like to do is set it up so that the delimiter still applies to the mailbox but sends everything to the default inbox instead of a directory for every unique value after the delimiter (i.e. mail to "myemail+thing@mydomain.com" and "myemail@mydomain.com" would both go to the inbox, not a different directory). Is this possible?