Error retrieve mail from Verizon or others (port issue?)

[DavJenkins]

I have 7 email accounts that I routinely monitor using both the iPod Touch and the Kindle Fire HD. I am able to check all 7 of them from the Kindle, either with OpenVPN up or down. On the iPod Touch I am able to check all 7 with the VPN down. But, as soon as I bring the VPN up and attempt to check mail, I get a pop-up:

Cannot Get Mail - The mail server "pop.verizon.net" is not responding. Verify that you have entered the correct account info in Mail settings.

And I get the identical message for each of the three failing accounts while the other 4 continue to work correctly.

The offending accounts are (as required by the respective servers) configured to use ports 993 or 995 (as appropriate) for retrieving email. Again, with the VPN down, they all work fine. And they all work fine with the VPN up on the Kindle.

Any thoughts or suggestions?

Before I determined that it was all working correctly on the Kindle, just not on the iPod, and therefore most likely related to the iOS OpenVPN implementation, I attempted to contact proXPN but... I will be charitable and just say that they were of no help.