NIS 2010. E-mail error. 503 Administrative prohibition

Hello!

I've got Norton Internet Security 2010 in Russian.

This pop-up message appears on my desktop some time after I connect to internet.

The title of the message is "E-mail ERROR".

I don't try to send e-mails through mail.ru server, so I have no idea where this error message comes from!

Is this a virus? I scanned my computer several times but NIS didn't find anything suspicious.

 

error.JPG