25 socket error from GMail (postfix, dovecot, ubuntu 14.04)

I’m getting the following error when trying to send mail to a mail server I’ve set up:

The recipient server did not accept our requests to connect. Learn more at http://support.google.com/mail/bin/answer.py?answer=7720
[(10) mail.mydomain.com. [123.456.789.123]:25: socket error]

My MX records check out when I put them through mxtoolbox.com. However, I can’t seem to get through via SMTP despite the following UFW status:

Status: active

To                         Action      From
--                         ------      ----
22                         ALLOW       Anywhere
9999/tcp                   ALLOW       Anywhere
80/tcp                     ALLOW       Anywhere
Anywhere                   ALLOW       24.62.28.170
443/tcp                    ALLOW       Anywhere
25/tcp                     ALLOW       Anywhere
993/tcp                    ALLOW       Anywhere
587/tcp                    ALLOW       Anywhere
465/tcp                    ALLOW       Anywhere
22 (v6)                    ALLOW       Anywhere (v6)
9999/tcp (v6)              ALLOW       Anywhere (v6)
80/tcp (v6)                ALLOW       Anywhere (v6)
443/tcp (v6)               ALLOW       Anywhere (v6)
25/tcp (v6)                ALLOW       Anywhere (v6)
993/tcp (v6)               ALLOW       Anywhere (v6)
587/tcp (v6)               ALLOW       Anywhere (v6)
465/tcp (v6)               ALLOW       Anywhere (v6)

I’ve followed the ARS guide for setting up a mail server with the exception of the DKIM setup which I did via port rather than user (it seems to be working just fine).

Outgoing mail sends just fine and does not get caught in spam filters. I remember when I initially set up the server I did some kind of mail configuring to send Tripwire reports and I’m wondering if that’s messing everything up.

Barring suggestions here, I’m thinking I might take a mulligan and try again.