Sendmail works but SMNT doesn' recognize the recipient ! Can somebody give me a hint, please ?

[Daniel Pope]

Hello,
I succeeded to configure sendmail and I can send e-mails from my dedicated server but even if I added a MX record for handling the e-mail I got always the following message:

This message was created automatically by mail delivery software.
A message that you sent could not be delivered to all of its recipients. The
following address(es) failed:

  admin at ticket2print.com:
    SMTP error from remote mailer after RCPT TO:
    <admin at ticket2print.com>:
    host ticket2print.com [64.232.5.110]:
    550 <admin at ticket2print.com>... Relaying denied


Can somebody send me a hint, please ?

Thank you in advance !!!