Mail always rejected to this particular email address, why?

This is using MS Exchange 2010 server. Recently, my users always got mails rejected when they attempt to send mails to email domain. The replied message is as follows: #554 5.7.1 Blocked by Reputation Enabled Defense: go to<my mail server IP>&u=2dd6d743dfd267b8&d=794add117df5f07b ##

I checked my mailserver IP against MXToolsbox, and found that it was only listed in one of the RBL, called "justspam". Mails sent to other domain without problem. What could be the problem?

Thanks in advance.
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Zephyr ICTCloud ArchitectCommented:
Did you use the link in the message to check your reputation? (<my mail server IP>&u=2dd6d743dfd267b8&d=794add117df5f07b)?

If it by chance uses that specific list where you're blacklisted your mail can be rejected/blocked ...
Marwan OsmanCommented:
is #554 5.7.1 your domain?
Will SzymkowskiSenior Solution ArchitectCommented:
Whatever anti-spam appliance the domain is using is blocking your domain from sending to it. The anti-spam appliances use the RBL lists on the internet to determine the domains that are flagged as spammers. If you have checked using and you are not blocked this could have been a manual entry entered on the receipients anti-spam appliance.

I would just contact them stating to check there appliance.


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MichaelBalackAuthor Commented:
Hi Marwan,

No, wasn't my mail hostname, think should be recipient's mail host.
MichaelBalackAuthor Commented:
Hi Will,

I agreed with you. I already feedback to the incident to the recipient. See what is the reply from them?
Marwan OsmanCommented:
Hi Michael

What did they reply?
MichaelBalackAuthor Commented:
Hi Marwan,

No reply from them up to this moment. Anyway, only this domain is rejecting our mails. We got no problem with the rest.
MichaelBalackAuthor Commented:
Will pointed out the important point. My Mailserver IP wasn't blacklisted, and so, it was due the borderware.
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