On premise exchange sending to any microsoft o365 account

Dave Johnson 1 Reputation point
2020-07-22T16:29:59.507+00:00

i i have various customers who have exchange on premise, all smarthost via isp. When sending from the to any microsoft o365 hosted all emails go to junk folder, we have spent hours and can find no solution emails meet the requiredment dmark, spf dkim all ok . Please help

thanks, all recipients cant have to whitelist cannot fine reason for email going into junk

Microsoft Exchange Online Management
Microsoft Exchange Online Management
Microsoft Exchange Online: A Microsoft email and calendaring hosted service.Management: The act or process of organizing, handling, directing or controlling something.
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  1. Andy David - MVP 142.3K Reputation points MVP
    2020-07-22T16:32:38.797+00:00

    Can you grab a sample internet header from an example message from one of those recipients and post here ( scrubbed of personal domain and user info)

    Are you 100% positive you are passing DMARC and other auth tests?

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  2. Yuki Sun-MSFT 40,871 Reputation points
    2020-07-23T08:55:15.487+00:00

    Are these affected customers from different Exchange organizatioins?

    Agree with AD-7937 that it's suggested to go through the internet headers of a problematic message and see if any clues can be detected.

    Besides, Microsoft 365 may not accept email from senders who fail a reverse-DNS lookup, so it's also suggested to check if the PTR records have been configured properly. You can aslo try to work with the recipient side to submit a false positive message to the Microsoft Spam Analysis Team to help evaluate and analyze the message. See My email landed in the recipient's Junk Email folder.