ZENGHOST

Hello, I just signed up for a new (deluxe) account today and have a question about my email. I already have a webhosting service that I'm switching from over to you guys. I still have it up and running and have not changed the DNS on my domain name yet. I followed all of the instructions for the "seamless" move, but wanted to clear this up first. I uploaded my site to my surpass account and can see it by going to the IP address given to me. So according to what I have read, if I change the DNS on my domain name, within 72 hours my site will go from my old webhost to this new one, correct? My question is about my email addresses. I have 3 or 4 email addresses associated through the other webhost, when I change the DNS on my domain, will the email switch over immediately, or will there be a break in service? I've already set up the email accounts in my cpanel, so I'm thinking that there won't be a break, but I wanted to make sure. I hope that is a clear enough question. Thank you for your time.