Outlook App / Outlook Web custom infobar messege

Question

Hello,

I would like to educate users that they should use third-party document management storage instead of e-mail's attachments. So I looking a way to display a messege in Outlook's inforbar (like mail tips or policy tips ) for specific conditions:

• all receipients are from my organization (domain)
• a file is attached

Could you advice me how can I do it? Data Loss Prevention don't allow to filter external recepients from custom rule.

Answer 1

There's no way to do this natively, you will have to develop some kind of add-in. DLP is a different use case and not applicable here, and the other functionality that comes close to this is MailTips: https://learn.microsoft.com/en-us/exchange/clients-and-mobile-in-exchange-online/mailtips/mailtips
Neither of these will be a good match for your scenario though, thus my recommendation is to look into custom solution.