Associating leads with visitors

I've put a lot of time and money into Zoho only to find that it seems to be much more difficult to associate a visitor with a lead. I assumed you would be able to email a lead and if he/she clicked on the link provided they would then be associated with a visitor profile. That doesn't seem to be the case though.

While the visitor tracking is useful, it's very limited if it cannot be associated with lead profiles on a broader basis. Particularly if you have a following prior to using Zoho..

I like Zoho, but this is a huge limiting factor that has me looking elsewhere..