We are running Exchange on-prem with two accepted domains. Both domains follow the same Exchange mail-flow rules, outbound mail-flow and both have correct SPF records. One of these two domain's emails gets marked as spam with SCL:5 and one does not. This domain's emails are ONLY marked as spam when sending to Exchange Online mailboxes. I can not find a single difference between how the two domains are configured nor why one is marked as spam and one is not. How do I get the domain not marked as spam? I'm lost as where to go next.
Country/Region: US
Language: en
Spam Confidence Level: 5
Spam Filtering Verdict: SPM
IP Filter Verdict: NLI
HELO/EHLO String: *******
PTR Record: InfoDomainNonexistent
Connecting IP Address: *******
Protection Policy Category: SPM
Spam rules: (13230001)(4636009)(356005)(2616005)(81166007)(7116003)(3480700007)(86362001)(82310400005)(7066003)(24736004)(8676002)(6916009)(36005)(166002)(108616005)(19627405001)(1096003)(5660300002)(8936002)(156005)(58800400005)(336012)(36756003)(83380400001)
Source header: CIP:*******;CTRY:US;LANG:en;SCL:5;SRV:;IPV:NLI;SFV:SPM;H:********;PTR:InfoDomainNonexistent;CAT:SPM;SFS:(13230001)(4636009)(356005)(2616005)(81166007)(7116003)(3480700007)(86362001)(82310400005)(7066003)(24736004)(8676002)(6916009)(36005)(166002)(108616005)(19627405001)(1096003)(5660300002)(8936002)(156005)(58800400005)(336012)(36756003)(83380400001);DIR:INB;
Unknown fields DIR:INB;
