so Canada has a really tough anti spam law called CASL. At its heart is the whole concept that you are not allowed to email any leads/prospects without their express permission to email them. 

"... sending of commercial electronic messages without the recipient's consent (permission), including messages to email addresses and social networking accounts, and text messages sent to a cell phone;

...

"

So here is my problem:

there currently is an email opt out button, that will be looked at by any email leaving zoho to see if this flag is flying or not. However, there doesnt seem to be a mechanism to see if an email is ALLOWED to go in the first place. 

How are other Canadian Companies handling emailing prospects/leads via Zoho without having a place to log this and see if emailing this lead/prospect is allowed in the first place?

my possible solution:

have a IS CASL COMPLIANT check box (with date/time indicated) which must be checked YES for any email to go out.

So the system would check IS CASL COMPLIANT and EMAIL OPT OUT to determine emailing capability.