text change only in BP menu


i am trying to change "send email" in the BP menu to "group email" for the "BuddyPress Group Email" plugin.
i did manage to change it but the heading below also apparently has the same text and is changing as well.
the below heading should read "send email to group".

i managed to change it without specifying anything for "in this text domain" as i do not know the text domain for this plugin.
- would it be wise to add this specific text domain just in case these words happen to appear somewhere else on the site ? if so, what exactly would be the text domain for this plugin ?
- how can i change "send email" just in the BP menu and not the heading below ?

any kind assistance in this would be greatly appreciated.

thanks again in advance.