What is meanings of 'X-Microsoft-Antispam-Mailbox-Delivery' and 'OFR:CustomRules'?

Daegeun Ryu 46 Reputation points
2021-05-31T09:52:04.443+00:00

Threats
Spam
Threats / Detection technologies
Spam / General filter
Delivery action / Original delivery location
Delivered to junk / Junk folder
Latest delivery location
Junk folder
Protection policy/action
Spam policy/Move to junk mail folder
X-Microsoft-Antispam-Mailbox-Delivery: ucf:0;jmr:1;auth:0;dest:J;ENG:(20160513016)(750129)(520011016)(944506458)(944626604);

Threats
None
Threats / Detection technologies
None
Delivery action / Original delivery location
Delivered to junk / Junk folder
Latest delivery location
Junk folder

X-Microsoft-Antispam-Mailbox-Delivery: ucf:1;jmr:0;auth:0;dest:J;OFR:CustomRules;ENG:(20160514016)(750129)(520011016);

I received the same mail and both were moved to the Junk folder.
But, the above mail was detected from EOP to Spam, and the below mail was not detected.

The only difference between the two mails is that 'OFR:CustomRules' is added to the 'X-Microsoft-Antispam-Mailbox-Delivery' header.

I've looked up the meanings of 'X-Microsoft-Antispam-Mailbox-Delivery' and 'OFR:CustomRules' but I'm asking because it's not listed anywhere.

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Accepted answer
  1. Yuki Sun-MSFT 41,376 Reputation points Moderator
    2021-06-01T03:02:29.407+00:00

    Hi @Daegeun Ryu ,

    I tried searching a lot regarding 'X-Microsoft-Antispam-Mailbox-Delivery' and 'OFR:CustomRules' but found no explaination or documentation either.

    As per the 'X-Microsoft-Antispam-Mailbox-Delivery' header, during my research, I noticed the following two links which talks about the same matter, but from the discussion there, it seems that so far there's still no decription for this header documented in official articles anywhere.
    Please add descriptions of X-Microsoft-Antispam-Mailbox-Delivery header
    Include documentation on X-Microsoft-Antispam-Mailbox-Delivery header

    Regarding 'OFR:CustomRules', literally seems to be related to rules, that is, the message has reached the Junk folder because of a rule. So I'd recommend starting by reviewing the recipient's side inbox rules. To help troubleshoot, you could temorarily disable all Inbox rules, and see if resending the message will still make it reach the junk folder with 'OFR:CustomRules' in the header.

    A relevant thread which mentions 'OFR:CustomRules' in the best answer for your reference:
    Transport rule for authenticated sender
    101276-1.jpeg


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