after hours of fiddling i discovered that vodafone will not allow unencyrpted emails to be sent over their mobile network. This is certainly true for their dongles, port 25 might still work for contract phones. Receiving might still be working normally.

this message might appear:

Task 'abc@xyz.com - Sending' reported error (0x800CCC67) : ' The server responded: 421 cannot connect to server'

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The only problem I can find that would match these symptoms, is that you're trying to connect un-authenticated - as I believe our network will intercept connections made over Port 25 and re-direct you to the now defunct send.vodafone.net server. It's possible this is still happening.

Double-check that Authentication is enabled, SSL is enabled, and that it's using Port number 465.

NB: should be secure and possibly authenticated in both directions
add other smtp servers here