Saved Message Search criteria for outgoing emails

We created a saved messgae search to report outgoing emails per user.

If any user sends email to multiple receipents, this search result shows same copy multiple times as NS attaches same copy to all recipients records. Instead we want to get only one copy in results.

Search should exclude same email next time if it's createdate matches with previous record createdate.

Thought to compare date of (internal id and internalid-1) with formula(Numeric) or Formula(Date)

date({internalid}) - date({internalid}-1), if value equal or difference 0 not to include that record in result.

I am new to set these expressions. Please help to get an idea to write different way or different functions/fields if this is not the correct way of doing... Thanks for your help.!