This idea has been merged into another idea. To comment or vote on this idea, please visit IDEAMLCT-I-21 Ability to have a disclosure for incoming Internet email.
Customer need to inform their mail users that the mail comes from the External domain, so before opening any external mail, users will be more cautious.
For this, customer need to append a line on the mail body for the external mail that "This is a External mail, be cautious before opening any attachment for the same.
This functionality is require on SCN.