Disable NDR (Non Delivery Report)

Sendmail:

Edit the file : /etc/mail/sendmail.mc

Change

define(`confPRIVACY_FLAGS’, `authwarnings,novrfy,noexpn,restrictqrun’)dnl

to

define(`confPRIVACY_FLAGS’, `authwarnings,nobodyreturn’)dnl

Save the file.

updated the config :

 m4 sendmail.mc > sendmail.cf

Restart the service :

/etc/init.d/sendmail restart

Exchange 2013:

Set-RemoteDomain * -NDREnabled $False.

This will disable sending NDR for default Remote Domain.