form mail errors

[sami]

This message was created automatically by mail delivery software.

A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:

sdf@blabla.com
SMTP error from remote mailer after MAIL FROM:<admin@xwhatever.com> SIZE=2924:
host flmx-1.blabla.com [65.34.1.12]: 553 5.1.8 <admin@xwhatever.com>... Domain of sender address admin@xwhatever.com does not exist

------ This is a copy of the message, including all the headers. ----



how do i fix this problem?

[sami]

This email came to my mailbox, after directadmin was suppose to send out the welcome email to the new client I setup.

[nobaloney]

Both the username and the domain name must exist and be resolvable, or many hosts won't accept the email.

Jeff