Strange E-mail errors...

Good aftenoon All,

I have a strange error..

one of our cpanel serves started doing weird things...

The server started boucing e-mails:

===== start error message =====
The following recipient(s) could not be reached:

customerservice@[domain.tld] on 06/03/2007 2:29 PM
There was a SMTP communication problem with the recipient's email server. Please contact your system administrator.
<[outbound mail server] #5.5.0 smtp;550-"The recipient cannot be verified. Please check all recipients of this>
===== end error message =====

The weird part is this... I tried checking the users e-mail accounts and tried adding a test account to the domain to see if it was just that one account or the whole domain and i get the following error when trying to add the e-mail message:

===== cpanel screen output =====

Mail Account Maintenance

Account Created

The e-mail account 123@[domain.tld] with the login Permission denied: /home/[removed]/etc/[domain.tld]/passwd passwd and password 123 with a quota of 10 Megabytes was successfully created.

I have no idea what is going on... and its driving me nuts...

I've run /scripts/mailperm and the exim scripts from within whm.

Does anyone have any ideas or suggestions to help resolve this issue..??

Thanks in advance for your time.