Wagn's functionality here is at present just a very thin wrapper around Ruby-on-Rails' ActionMailer (which in turn is using an external smtp gem). My guess is that the best answers at present would probably come from the rails community. Perhaps this is helpful:

 

http://stackoverflow.com/questions/13408898/hostname-does-not-match-the-server-certificate-cannot-send-email

 

To translate that into WagnSpeak, you might try something like this in wagn.yml

 

smtp:

openssl_verify_mode: false

 

if that doesn't work, then I would suspect that googling the main error message ("hostname does not match the server certificate") would be likely to turn up other options.