How Good Is Mail Search?

I am thinking of switching to Zoho hosted mail. I have approx. 1.3G of mail in many hundreds of folders organized hierarchically. It goes up to 7 layers deep. I have to often pull up messages from previous years. Would I be able to search the entire content by using Zoho search?

Right now I use an IMAP account. My desktop client is Thunderbird, the server is MailXchange hosted by 1and1. The server allows a multi layer structure, but the search function is useless. Because of that I have to use TB to be able to search through the entire content.

Thanks in advance for the input.