Microsoft Outlook MailTips is an opt-in feature for Exchange Server 2013 that will send alerts to end users when they are about about to click "reply all" to a large distribution list, send sensitive information to someone outside the organization or send a message to someone who is out of the office.
MailTips will not work if:
- An end user is working in Outlook's offline mode.
- A message has more than 200 intended recipients.
- A message has more than 250 characters.