I think what it is is, cox just like verizon wont allow sending mail unless you are using their smtp server? Anyways, I think I can get around that by having outlook use the isp smtp server to send the test email. Hopefully verizon will whitelist my domain sooner than later.
I setup squirrelmail last night, works great with your setup. One thing I noticed is it's folder handling abilities isn't as good as I'd like.
If you have a folder named Online Transactions, it dosn't work because looking for a directory Online Transactions causes it to find /Online/ which dosn't exist. In addition the created directories are not supported as far as the new mail notification and quota plugins are concerned. I'm sure the code can be edited for such purposes, but I am not that fimilar with php yet. Yea YET! :P