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ErikMHedges avatar image
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ErikMHedges asked ErikMHedges commented

Unable to modify Mail-Enabled Security Group to Receive External Mail in M365

We are in a hybrid environment with M365 (AD sync only and have migrated from on-prem exchange 9 months ago). I am unable to modify a mail-enabled security group in M365. I receive the message in the Exchange Online Admin Center "You can only manage this group in your on-premises environment". We killed our on-prem Exchange Server several months ago after migrating. I also do not see an option to set this in our on-prem AD. How do I go about modifying this?

Thank you!

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AndyDavid avatar image
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AndyDavid answered ErikMHedges edited

What do you want to modify? You can always use ADUC or set-adgroup and let it sync,

Note, technically to be supported you need at least one Exch Server on-prem to manage:
https://docs.microsoft.com/en-us/exchange/decommission-on-premises-exchange



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@AndyDavid I need to modify a mail-enabled security group to allow for external sharing. I do not see that option in ADUC. Your note kind of irks me - not towards you - I appreciate the answer, but towards our consultant who said there is no need to have an on-prem exchange server after migration!

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AndyDavid avatar image
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AndyDavid answered ErikMHedges commented

You can use powershell or ADUC
With ADUC, find the group and access it properties and set:

msExchRequireAuthToSendTo

to $false to allow external users to send to it.
Once it syncs, it should work in 365

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@AndyDavid Thank you so much!

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