Email Problem (421 Requested action aborted)

Hi,

Please advice, one of my client encounter below problem.
Any clue what should I do?
Thanks you very much

-------------------------------

Subject: Warning: message 1XW5Ur-0003VS-K9 delayed 24 hours

This message was created automatically by mail delivery software.
A message that you sent has not yet been delivered to one or more of its
recipients after more than 24 hours on the queue

The message identifier is: 1XW5Ur-0003VS-K9
The subject of the message is: Re: Bebe au lait New Order
The date of the message is: Mon, 22 Sep 2014 22:25:26 +0700

The address to which the message has not yet been delivered is:


Delay reason: SMTP error from remote mail server after initial
connection:
host mx01.1and1.com [74.208.5.21]: 421-perfora.net (mxeueus001) Nemesis
ESMTP Service not available
421 Requested action aborted: local error in processing

No action is required on your part. Delivery attempts will continue for
some time, and this warning may be repeated at intervals if the message
remains undelivered. Eventually the mail delivery software will give up,
and when that happens, the message will be returned to you.

 

Hi,

Thanks your for your help please close my thread.

Many Thanks :D