Plesk WebMail function 550 ERROR

[viecas]

This is the error when i try to send a outgoing email. but incoming email is working fine.

MailEnable: Message could not be delivered to some recipients.
The following recipient(s) could not be reached:

Recipient: [SMTP:[email protected]]
Reason: Remote SMTP Server Returned: 550 Requested action not taken: mailbox unavailable or not local

 

[IgorG]

Look at this MailEnable KB article - http://www.mailenable.com/kb/content/article.asp?ID=ME020476
I hope it will help.