Gmail requires SSL/TLS support to work properly and I am a faithful Gmail user. I noticed a few other on here are as well. So here is a fix to get Gmail (or another encrypted mail server) working with OpenGoo:
Download and install Stunnel (http://www.stunnel.org/
It is a free program which will sit on your computer and download your email on command. It supports SSL/TLS.
Now edit your configuration file to look something like:
; Use it for client mode
client = yes
; Service-level configuration
accept = 110
connect = pop.gmail.com:995
accept = 25
connect = smtp.gmail.com:465
Now in OpenGoo put in your full email address for username and your password. Set your Pop3 server to 127.0.0.1 and your smtp server to 127.0.0.1 with port 25.
It should now work!