On 8/9/2019 12:15 PM, Kevin Miller wrote:
Sorry for the OT post, but I'm stumped and hope someone here can enlighten me.
When sending to a mimecast users, our mailserver timed out with. Looking at
the logs, I see:
Aug 9 07:39:48 smtp postfix/smtp[31712]: 060641011CF: host
us-smtp-1.mimecast.com[205.139.110.139] said: 451 Hostname is not authorized -
https://community.mimecast.com/docs/DOC-1369#451 [3xVXmRAsN4awNrHIyHCW5Q.us94]
(in reply to RCPT TO command)
Looking at the web page referred to in the log entry I find this:
451 Hostname is not authorized Omni Directional hostnames is enabled.
Disable Omni Directional hostnames.
I did a web search but can't find any other reference to "Omni Directional hostnames".
What are they referring to that they don't like about the sending hostname (smtp.ci.juneau.ak.us)?
No other domain is rejecting messages based on the hostname and the phrase "Omni Directional
hostnames" doesn't seem to be industry standard nomenclature. At least not that I can find in
my searches.
I sent a query to postmas...@mimecast.com which was duly rejected (not awfully
surprised):
'postmas...@mimecast.com' (postmas...@mimecast.com)
Your message couldn't be delivered because delivery to this group is restricted
to authenticated senders. If the problem continues, please contact your email
admin.
Again, sorry for the OT post but if anyone knows what the heck they're talking
about I'd appreciate it...
...Kevin
--
Kevin Miller
Network/email Administrator, CBJ MIS Dept.
155 South Seward Street
Juneau, Alaska 99801
Phone: (907) 586-0242, Fax: (907) 586-4588 Registered Linux User No: 307357
I'm guessing this is something about FCrDNS for your IP, and/or your
HELO hostname doesn't have an A record matching the IP.
-- Noel Jones
