Update Set-Mailbox.md

The parameters "MessageCopyForSendOnBehalfOfEnabled" and "MessageCopyForSentAsEnabled" currently do not specify that they are available on for Shared Mailboxes, misleading customers and engineers when they're trying to manipulate this behavior.

Author: Cloud-Writer

exchange/exchange-ps/exchange/mailboxes/Set-Mailbox.md

@@ -4221,7 +4221,7 @@ Accept wildcard characters: False
 ```
 
 ### -MessageCopyForSendOnBehalfEnabled
-The MessageCopyForSendOnBehalfEnabled parameter specifies whether to copy the sender for messages that are sent from a mailbox by users that have the "send on behalf of" permission. Valid values are:
+The MessageCopyForSendOnBehalfEnabled parameter specifies whether to copy the sender for messages that are sent from a mailbox by users that have the "send on behalf of" permission. This parameter is available only for shared mailboxes. Valid values are:
 
 - $true: When a user sends a message from the mailbox by using the "send on behalf of" permission, a copy of the message is sent to the sender's mailbox.
 
@@ -4242,7 +4242,7 @@ Accept wildcard characters: False
 ```
 
 ### -MessageCopyForSentAsEnabled
-The MessageCopyForSentAsEnabled parameter specifies whether to copy the sender for messages that are sent from a mailbox by users that have the "send as" permission. Valid values are:
+The MessageCopyForSentAsEnabled parameter specifies whether to copy the sender for messages that are sent from a mailbox by users that have the "send as" permission. This parameter is available only for shared mailboxes. Valid values are:
 
 - $true: When a user sends a message from the mailbox by using the "send as" permission, a copy of the message is sent to the sender's mailbox.