On an ASA I administer there is a policy-map in place which implements "inspect ESMTP". I've reviewed what this does, and in my (rather uninformed) opinion at first blush it looks to be a good thing to implement. It is however impacting the ability to send mass emails from lists with over 50 recipients according to our domain admins. They want to remove this inspection to alleviate the problem.
Is ESMTP inspection a solid control to leave and place, or is removal safe? If I don't want to remove it, is there a way to see what in the control is preventing mail from being sent and possibly alter that one element of it rather than removing it altogether?