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 remote.mydomain.com for the following reason:
5.1.0 Sender denied
The following recipients did not receive this message:
Please reply to <Postmaster@mx.bigpond.com>
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.