Exchange 2013 - Limit number of external recipients


I was wondering if any1 know a way to limit number of external recipients (to any number, lets say 50), so if someone try to send email to more then 50 users they get rejected with NDR or some notification.

Now, i know there are following options, but they are not good:
1. Recipients --> mailboxes --> <username> --> edit -->  mailbox features --> mail flow --> and then to set Recipient limit since this will limit number of internal recipients as well...
2. Mail flow --> send connectors --> … Organization transport settings --> limit number of recipients.. this will limit number of internal recipietns as well..
3. Throttling policy..i have tried with this, but didnt find any good for this type of problem.

I have seen that there is option: PickupDirectoryMaxRecipientsPerMessage, (Set-TransportService Mailbox01 -PickupDirectoryMaxRecipientsPerMessage xxx), but im not shure if this is global or hwat...

Is there any other way, am i missing something?

LVL 19
IvanSystem EngineerAsked:
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Ankit PareekOnline MarketingCommented:
Set-TransportConfig -MaxRecipientEnvelopeLimit 1000  use this to increase recipient number size
for more details you can read the following thread
make sure to changes you have administrative privileges because only user can't able to do these changes for exchange account
Minecraft_ EndermanCommented:
Actually, we cannot configure this setting. We can just configure the recipients limit per message, including both internal and external recipients.

All the message size limit, we can refer to this technet document for exchange 2013:

And message throttling refers to a group of limits that are set on the number of messages and connections that can be processed by Exchange Server 2013. So throttling policy also doesn’t work for this situation.

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