I got an email from one of my clients stating they cannot receive an email to a certain person. Here is the message the recipient receives.
This email is being returned to you because the remote server would not or could not accept the message. The registeredsite servers are just reporting to you what happened and are not the source of the problem.
The address which was undeliverable is in the section labeled:
"----- The following addresses had permanent fatal errors -----".
The reason your mail is being returned to you is in the section labeled:
"----- Transcript of Session Follows -----".
This section describes the specific reason your e-mail could not be delivered.
Please direct further questions regarding this message to your e-mail administrator.
----- Transcript of session follows ----- ... while talking to
>>> RCPT To:<firstname.lastname@example.org>
<<< 550 Unable to add email@example.com because host 188.8.131.52 is listed on bl.spamcop.net
550 5.1.1 <firstname.lastname@example.org>... User unknown
<<< 554 no valid recipients, bye
451 4.4.1 reply: read error from smtp1.msp.securence.com.
My Spam filter uses the IP's 184.108.40.206 and 220.127.116.11.
The Exchange server is using 50.251.186.***
I cannot figure out how they claim that his email address is going to 18.104.22.168.
Is this something on the senders end or my end?