Group Policy and Exchange - Restricting emails to DL's

We have 2 OU's in AD, one titled Internal ONLY DL's and the other Internal/External DL's. I noticed that they are controlling whether an external sender can send to the DL's depending which OU it's in, regardless of the Exchange settings on the DL's.

There's no direct GPO linked to these OU's, only the default. I can't find out how these OU's are controlling the DL's. I looked for 3rd party software on the server but there was none.

Any idea?
Scotch TechITAsked:
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Derek SouterITO Svc Delivery Cons IIICommented:
sounds like exchange transport policies - which version of Exchange?
Scotch TechITAuthor Commented:
Derek SouterITO Svc Delivery Cons IIICommented:
here's a good article on the transport rules

Transport rules can apply to individual OU's in Exchange 2013

have a look and see if there are any configured in your exchange organisation

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Seth SimmonsSr. Systems AdministratorCommented:
No comment has been added to this question in more than 21 days, so it is now classified as abandoned.

I have recommended this question be closed as follows:

Accept: Derek Souter (https:#a42446780)

If you feel this question should be closed differently, post an objection and the moderators will review all objections and close it as they feel fit. If no one objects, this question will be closed automatically the way described above.

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