How to add the email option in the more options icon

[velvet]

In an incident we have the email option in the more options icon.   I need to add the email in the more options icon for Requests, Items, SCtask, and Problems.

[patbishop]

I have a requirement to add this to a custom table, however, it's a table that 2 different clients share. Is there a way to modify the ACL or visibility of the "Email" button based on HR Service?