We have got a problem on one of Exchange Bridge-Head Server which is generating NDR 5.1.1 only for the users of another domain in the same forest. We have 3 BH Servers out of which we have issue with one BH Server. When users are sending email to a DL, the NDR generates randomly for different set of users at random instances. We have increased the diag. logging to maximum, but can not see any errors other than the NDRs. We have checked all the DCs as well and no issues.
BH Server is in Domain A which is separate tree domain of the forest X. The users resides in Domain B which is a child Domain under the Root Domain X. The mailboxes resides on the mailbox servers of Domain A.
Only difference we can identify on this particular server that:
When we are searching some of the users of Domain B under Entire Directory on ADUC, it is not able to search the user. Whereas we are able search the same user when we specifically search the same user selecting the Domain B.
Urgent help is appreciated...