It's a problem I keep seeing referred to in many ways & if I understand it right Zoho do not have a solution that works.

If I'm wrong, let me know.

If you have for instance 400 leads & you email 250 of them from the mass email system then you cannot see a list separating those that were in the 250 who you sent to and those 150 you did not send to.

That seems to be a fact? The last activity time does not include mass emails (though it seems to include a 1:1 email) and the Modified Time is not altered by emails either. 

It seems a bit bonkers that you'd have so many tools but not this one? 

My intention is to find the other 150 & email them tomorrow when my daily 250 limit has run out. 

Could it be that this problem is not fixed as it makes that harder for me? I.E incentivises me to buy a bigger emailing package? 

If anyone can help, explain, deny or confirm this point I'd be very pleased.

Dan