BCC Dropbox Not Working

BCC Dropbox Not Working

Yet again my BCC Dropbox is not working correctly.
Whenever this is reported to support I'm told the issue is with my settings. After checking I have everything correct the problem eventually (after a week or two) decides to fix itself.

This time, I have checked my settings (which as usual are correct) and have found the BCC Dropbox is only delivering a copy to my Contacts, but not my Leads. Looking back this has been occurring for several weeks now, where it worked perfectly fine before that (I've made no changes to my system in this time).

Can someone please explain what I can do to fix this. 

I am seriously thinking it's time to go elsewhere, especially as sending directly from Zoho CRM can't tell me if my email has been delivered (and often they're not)!!