I am experiencing an issue where sending to this one domain we receive 554 sending address not accepted due to spam filter. Here is the output from if I telnet to the port and perform the task;

[root@pns-mail01 ~]# telnet 1.1.1.1 25
Trying 1.1.1.1...
Connected to 1.1.1.1.
Escape character is '^]'.
220 mail5.********
ehlo pns-mail01.*******
250-MAIL5.******** Hello [2.2.2.2]
250-SIZE 31457280
250-AUTH LOGIN CRAM-MD5
250 OK
mail from:<user@domainname.com>
554 Sending address not accepted due to spam filter

This is from the server. If i do the same from my desktop everything goes through okay. My IP address isn't blacklisted and neither is the receiving host. I haven't made any changes to anything except installed iRedAdmin-Pro-LDAP and this seems like the only domain this is happening to also out of atleast 30 other domains we send to.

==== Required information ====
- iRedMail version: iRedAdmin-Pro-LDAP v2
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): LDAP
- Linux/BSD distribution name and version: CentOS 6 64bit
- Related log if you're reporting an issue:
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