We have Exchange server 2013 and in our organisations we have more then 15000 applications which sends automated emails.  Unfortunately we had to allow anonymous relay in-order to let the applications send emails.

Are there any ticks, methods, etc. where in these applications can send authenticated emails ?

Thanks for your com

Hello

tip: if application can use any auth method create new receive connector, set that auth method and add application/server/ ip, if cannot select application by ip you can create new receive connector with listening one ip and set application to use that ip to send email.

From the application side authentication is not possible.

Hello

need to talk with application manager to develop auth to mail sending.