Email is blocked from only one user, not our whole domain

[confuzeduzer]

We have over 200 users on our Rackspace email account. Yet only one of our users is receiving a bounceback message saying his email is being blocked by SpamCop. Any suggestion why?

Rackspace keep looking into it and as soon as it is marked as fixed, it happens again. I have gone back and forth with them 5 times.

[Lking]

SpamCop blocks IP addresses not domains nor email boxes. If only one mailbox is being blocked I would look at the bounce message(s) and see who is bouncing and see if their is any clue as to why. (Keep in mind that some email managers are lazy and report a generic reason for blocking email ~ weather it applies or not.)

Some options that come to mine:

1.  The mail service has blacklisted the sender for some reason.

2.  The bouncing service is blocking your domain/IP address AND only one of your accounts is sending them email.

Have you checked any of the several blocklist to see if you / you IP are listed?

 

[confuzeduzer]

We have a monitor that informs us when we are on a Blacklist. We have not been on a blacklist for a while.

 

I mispoke when I mentioned domain. What I meant was our IP was allegedly blocked, but it is only affecting one user.

[petzl]

1 hour ago, confuzeduzer said:

We have a monitor that informs us when we are on a Blacklist. We have not been on a blacklist for a while.

 

I mispoke when I mentioned domain. What I meant was our IP was allegedly blocked, but it is only affecting one user.

Would help if you disclosed the IP?

Your IP is not the only IP a blacklist looks for. Possibly users IP is blocklisted as a source 
Tell your user to scan for malware and change password If Microsoft Windows Defender is available to them, use it!