Well, as it turns out I had the domain still attached to the shared hosting account after I changed it to point to the new server. After removing...
Turns out its all about the server not properly authenticating, example here: Anyone know how to properly set it up?
Even more confusing, I can send and receive mails from my Yahoo account, but I several e-mails set up on some shared hosting over at HostGator....
Followed this guild here: http://www.howtoforge.com/virtual-users-domains-postfix-courier-mysql-squirrelmail-ubuntu8.10 After a bunch of fiddling...
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