Alot of Mail Bounces???

[SetLar8]

Hi, a client of mine is complaining he is recieving alot of email bounces after he is sending email, the following are just some of them:

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****@yahoo.co.uk
Delay reason: SMTP error from remote mail server after end of data:
host mx2.mail.ukl.yahoo.com [217.12.11.64]: 451 mta100.mail.ukl.yahoo.com Resources temporarily unavailable. Please try again later [#4.16.5].

****@****.net
SMTP error from remote mail server after RCPT
TO:<****@****.net>:
host mx1.triera.net [213.161.0.27]: 550 <****@****.net>:
Recipient address rejected: User unknown in virtual alias table

****@****.com.br
Delay reason: SMTP error from remote mail server after RCPT
TO:<****@****.com.br>:
host mx.oi.com.br [200.222.115.71]: 450 <****@****.com.br>:
Recipient address rejected: Temporary failure

****@yahoo.co.uk
Delay reason: SMTP error from remote mail server after end of data:
host mx2.mail.ukl.yahoo.com [217.12.11.64]: 451 mta128.mail.ukl.yahoo.com Resources temporarily unavailable. Please try again later [#4.16.5].

****@****.edu
retry timeout exceeded
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Can anyone tell me if this is a problem with the server at my end and if it is how i could remedy the problem.

Thanks.

[cLub2Share]

I'm also having this problem anyone have any commants about this ?

[mehrdad abed]

same problem,

[Murtaza_t]

Well it clearly states in the error "SMTP error from remote mail server" that the problem is at the other end.

It is either a problem with remote server or you have been blocked to send mails with certern headers.

[problemsolver]

Well it clearly states in the error "SMTP error from remote mail server" that the problem is at the other end.

It is either a problem with remote server or you have been blocked to send mails with certern headers.

Quite possibly that is the error the user is receiving when he is trying to send e-mail from an external source through his own server. I am also encountering problems with mail on my server ever time a new mail user is added to an account. The current error I am getting is:

"<*@*.*>: Recipient address rejected: User unknown in virtual alias table"

I checked /etc/valiases/domain.com and everything seemed fine. Does anyone have any ideas?