Mail suddenly stopped sending using VPN

Suddenly after 6 months of using a VPN, icloud mail will not send on my rMBP, I've tried various vpn cities, they all used to send but now I get the 'could not contact server' issue. It took a while before I realised it was the vpn and I've tested it on and off many times now to be sure.

Thing is it's always been fine. It receives mail ok with the vpn on, and my iPod is also able to send mail with the vpn on, but the macbook won't.

Any suggestions appreciated.