I just want to say I'm fully aware of the questions asked before regarding MX records. I did my homework and searched a lot on the site.
What I'm looking for, is a recommendation for a seamless MX record change for a client that I have. They currently have 6 users setup at Godaddy.com for their web/domain hosting, as well as email.
I'm moving them to Google Apps for email, but they want to try to avoid downtime. I've seen some Google Resellers promise that they can do the switch over in about 20 minutes. On the internet and basic logic tells me, MX propagation takes 24-48 hours.. but I want to keep an open mind about this. 20 minute changeover sounds pretty good. The question is, how would I be able to do that?
I've seen many people suggest to use a backup MX record of a higher value, and just change the priority when you're ready to go live. I've also seen people say that it wouldn't work because the mail gets split and it just doesn't work that way; that it would split 60/40.
So, what do you guys recommend is the most seamless way possible from Domain A to Domain B?
p.s. I know I tagged Exchange, but there's really no other zone that's related :)