SEND MAIL ISSUE Documentum

Hello,
We are beginners in the documentum 7.2 solution and we are looking for a solution to be able to send an automatic email to specific recipients (external or internal users) who will be selected by the end user in the document properties display window when importing (d2 import event) or modifying (dm_save event) document properties.

Also, we must respect the fact that if the user modifies the recipients who must receive the email, only the new recipients will have to receive it (the other users who have already been previously selected will not be recipients)

Thank you to answer us