A school I support is a CallPlus UFB customer with outgoing mail routed through smtp.callplus.co.nz.
Lately we've been having some mail bounce with messages coming back to us such as:
<<< 554 5.7.1 <(redacted)@(redacted)>: Recipient address rejected: [RBL_007] your ip 202.180.66.197 is listed on RBL and fortimail1.tranzpeer.net does not match mx197.tranzpeer.net
554 5.0.0 Service unavailable
<<< 554 5.5.1 Error: no valid recipients
Other bounce messages (from the Ministry of Education specifically) say "unknown recipient" for people in mid-conversation - usually messages before and since to/from the same recipient go through. I suspect the MoE server is really rejecting because of RBL matches too.
Sure enough, plugging 202.180.66.197 (mx197.tranzpeer.net) into anti-abuse.org's Multi-RBL scanner has it come up on SORBS, and plugging "202.180.66.0/24" into SORBS' database check comes up with this:
I've had this back from a member of the CallPlus business helpdesk:
It seems like the sender’s server check is having an error which causes the email to bounce back. We have checked on our end and it seems like the configuration is up to specification. The spam report from SORBS did not cause this problem as well.
Can some mail gurus provide their opinion as to what is going on here?
Thanks,
Andrew
edit: typo in subject line "bounce" -> "bounces"
