Why wont email work with VPN?

Everyone makes some unfounded assumptions.  I do NOT need private email, my VPN is NOT routed through an overseas provider, in fact the company is based overseas but uses servers based in the US.  The bandwidth through my VPN is NOT limited (I get my rated speeds whether or not I am on the VPN), I HAVE logged in through myemail.cox while on the VPN and it does work.  Even my banks and investment sites have no issues with my using a VPN while on their sites.  The ONLY issue is when sending mail and the client never gets a response back from Cox saying the sent mail has been moved to my sent folder (imap account) which also means the email did not actually get sent, yes I have tested this and the email is NOT sent.

I use a VPN as much for privacy as to thumb my nose at the FCC negating net neutrality as anything as well as Cox for being a poor provider of email services.  So basically I use a VPN because I want to, not because I have secrets to hide.  And if you think you don't need a VPN, you might want to investigate why all the PC/MAC sites are recommending folks use a VPN in their daily internet browsing.

Lastly, I have spent the last year turning off the VPN while using email but every so often I test Cox's response while on the VPN.  This thread was posted because there are still issues especially while sending mail.  Yes I can turn off the VPN while using email and usually do because of the issues but that doesn't mean I shouldn't post about continuous ongoing issues. 

In all honesty, this isn't a huge issue, but it exists.

Thanks to all that responded.

Warren