Mail and Sage - Problem sending

[PystCat]

Is anyone else having a problem sending email from Sage..?  I can suddenly receive mail but I can't send it... I keep getting the standard "Mail Delivery Failed - Will Try Again" message.  This happens with ALL email I send from Sage.

Does anyone know the support email address for On-Rev..?  I keep sending (from a different email) to On-rev at runrev.com but not getting any response.

Thanks
Paul