Usually you may receive error like:
Task user@domain.com - Sending reported error (0x800CCC67) : The server responded: 421 Cannot connect to SMTP server , NB connect error 1460
In most cases this is related to Avast Anti virus software or AVG Antivirus, but usually see this error with Avast in most cases..
Disable it. Close your email program and reopen it again and it should be working soon enough.
If it still does not work and maybe even before uninstalling Avast try changing the SMTP port in your Email Client (Mail Program) from port 25 to port 587 instead.
