Allow users to disable External Recipient MailTip
The newly added External Recipient MailTip is fine for those who feel it adds value, but is an unnecessary waste of real estate and can frustrate users who generally mail external recipients and therefore don't need this warning.
If it can't be removed, then please at least allow users to disable it.
Trevor Batt commented
This is a helpful notification, but you should be able to turn it off if it's not needed or applicable. I have an Exchange account with just one user, so everyone is "outside" my organization.