Some people cant send emails to my domain

I am having a complain from my client saying that some people try to send him an email and they have the following back email.

This Message was undeliverable due to the following reason:

Your message was not delivered because the destination computer refused
to accept it (the error message is reproduced below).  This type of error
is usually due to a mis-configured account or mail delivery system on the
destination computer; however, it could be caused by your message since
some mail systems refuse messages with invalid header information, or if
they are too large.

Your message was rejected by for the following reason:

     5.1.0 Sender denied

The following recipients did not receive this message:


Please reply to <>
if you feel this message to be in error.

The original message has been removed from the bounce message,

The server is SBS 2011 and exchange 2010.
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I would check the accepted IP range of the Receive Connector ... is this all from the same domain or is it various senders from multiple domains?
Kamalasekar ParthasarathyMessaging SupportCommented:


You have to check the destination domain and ask your email domain to be added in their accepte list in Email gateway servers.

Thank you
just to clarify the point from Raj - it is likely due to the recipient server's spam filter -- your domain may need to be exempted or whitelisted from filtering and try again
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flf4evaAuthor Commented:
I have some updates,

this problem is happening only from one source, to a specific user in my domain. so this problem is happening when is sending to however if will send to the email will go through.

hopefully this will clarify the problem
i will check the properties of the user from ecm - on the mail flow settings - Message delivery restriction

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Kamalasekar ParthasarathyMessaging SupportCommented:
This address might be blocked by some one of the destination domain.

Kindly ask him to send a email to with delivery receipt..

Also, please confirm this user abc having the issue with only that particular domain or any domain from outside/ inside.

Please confirm, We can try to fix this issue.
Adding to sekar_raj32's comments, you could also try to disable all antispam features from your client's server, then try again!! If works, then you'll have a better clue where to target your troubleshooting.
Kamalasekar ParthasarathyMessaging SupportCommented:
Kindly update this request.. if you have resolved it, please share the same.
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