NDR 550 5.7.1 Cross-forest send email to mailbox which forward to distribution group

Question

Hi,

We use ADMT to migrate domain from A to B, and also move some of the ex2016 mailbox in domain A to ex2019 in domain B. Some mailboxes in domain A configured auto forward to a domain A distribution group, the group set to delivery by “only sender inside my organization”

We found when domain B user send to these domain A mailboxes, they will receive a NDR from domain A Exchange said “Remote Server returned '550 5.7.1 RESOLVER.RST.AuthRequired; authentication required“.
Tested if they send to the group directly, the email can send out normally.

How can we solve the NDR problem so domain B user can send email to these mailbox and also forward to group?

Chong

Answer 1

Hi Chong,

Did you mean if Domain B mailboxes send to Domain A mailboxes (which are configured to auto-forward to distribution groups in Domain A), they would receive this NDR message?
If yes, I suppose it is the expected behavior.

The whole process would be like:

1. Domain B mailbox sends to a mailbox in Domain A
2. Due to the delivery option setting on the mailbox in Domain A, the message is redirected to the distribution group during transport
3. The forwarded message is considered sent from outside the organization, and since the group delivery option is "only sender inside my organization", the message gets rejected.

You may also see it via message tracking:

To solve this issue, you may create mailbox contacts for the mailboxes (which are currently in Domain B) on Exchange in Domain A and configure the distribution group to accept messages from these contacts ,and also the mailboxes used to forward to this group in Domain A.

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