How long will my mail be kept in my mail account?

How long will my mail be kept in my mail account?

I currently use yahoo and outlook express. I can keep emails forever on both of these, and sometimes I search my history 3, 4 even 5 years back. My friend told me on Zoho emails are kept for 12 months even if you haven't hit the data size limit of 10gb. Is this true? I really want to switch, but this would be terrible for me. And what about in the free account? Are emails only kept for 12 months?

Also, if I use the archive function and archive my eamils, will they still come up in a search?

I am hoping I get a great answer, I love the zoho interface and really want to switch. Thanks