Mail Delivery Problem - Maillog check

[kuhle]

I have a customer ([email protected]) who cannot send email to one particular domain (e.g. [email protected]).

When they send it, they receive the following failure notice:


> Hi. This is the qmail-send program at plesk.expat-email.co.uk.
> I'm afraid I wasn't able to deliver your message to the following
> addresses.
> This is a permanent error; I've given up. Sorry it didn't work out.
>
<[email protected]>:
> 83.142.xxx.xxx does not like recipient.
> Remote host said: 550-Verification failed for
> <[email protected]>
> 550-No Such User Here
> 550 Sender verify failed
> Giving up on 83.142.xxx.xxx.

I ran maillog at the same time and got the following extract:
Jul 5 16:15:09 plesk qmail-queue[1113]: scan: the message(drweb.tmp.xKlI56) sent by [email protected] to rcpts is passed
Jul 5 16:15:09 plesk qmail: 1183648509.099465 new msg 19941944
Jul 5 16:15:09 plesk qmail: 1183648509.099537 info msg 19941944: bytes 3120 from <[email protected] > qp 1114 uid 2020
Jul 5 16:15:09 plesk qmail: 1183648509.110419 starting delivery 932: msg 19941944 to remote [email protected]
Jul 5 16:15:09 plesk qmail: 1183648509.531516 delivery 932: failure: 83.142.xxx.xxx_does_not_like_recipient./Remote_host_said:_550-Verification_failed_for_<[email protected]>/550-No_Such_User_Here/550_Sender_verify_failed/Giving_up_on_83.142.xxx.xxx./

Can someone help me to pinpoint where the problem lies in delivering mail to that person?