One of my clients told me that they cannot send e-mail to me. The following error messages are received by them (i think it is generated by their mail server):
> This message was created automatically by the mail system (ecelerity).
>
> 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:
>
>>>>
[email protected] (after RCPT TO): 550-Verification failed for
>>>>
> 550-The mail server could not deliver mail to
[email protected]. The
> account or domain may not exist, they may be blacklisted, or missing the
> proper dns entries.
> 550 Sender verify failed
Is it the problem at my side or the problem at their side? If the problem is at their side, can I configure my account so that I will not have problem to receive their e-mails?
Thanks a lot!!