Postini, Spam, Employees using Zoho Mail

Postini, Spam, Employees using Zoho Mail

Greetings!  I love Zoho mail.  However, I do get spam each and everyday.  I'm getting ready to hire a couple of employees for my small business.

How do I prevent my new employees (who will also be using Zoho Mail) from clicking on Spam?

I've heard Postini is a great service; does Postini work with Zoho Mail?

If not, is there another application/service that integrates with Zoho Mail so that I don't have to worry about future employees clicking on links within Spam emails? 

I'm very, very, very concerned about this.

Any tips/information you can provide would be most helpful.