Hi anonymous user,
Agree with AshokM that you can try setting the SCL to Bypass spam filtering via the mail flow rules and see how it goes. Or you can try adding the email address of the sender to the Safe Senders list and Safe Recipients list on all user mailboxes:
Get-Mailbox -RecipientTypeDetails UserMailbox | Set-MailboxJunkEmailConfiguration -TrustedSendersAndDomains @{Add="test@abc.com"}
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