Questions regarding migrating email from one host to another

Question

I'm a web developer who also handles hosting setups. I often get clients who have an existing site hosted by some local company and it's a real PITA to try to setup a PHP/MySQL site on their hosting, so I prefer to just host sites through a LiquidWeb VPS that I have, with Linux, Apache, MySQL, PHP (LAMP) etc.

I'm trying to figure out how to smoothly move email hosting. The last time I changed the host for a client, it took a day or two for the new domain name settings to propogate, so some emails were going to their old host and some were going to their new host. Is there an easier way to handle that?

How hard is it to setup a seperate host for the email and their website, so that I can just leave email alone and only move the website? When I set the DNS for their domain name I'm just given an option for the domain name itself, not sub-domains such as mail.

What if a client is using Microsoft Exchange, but I want to use LAMP?

As you can tell, I'm a newb at this aspect, so please be patient :-)

Answer 1

My company does a similar service, What we did was this.

We have a cluster for their website, and a cluster for their email.

When we migrate email, we update the DNS and things start flowing the new direction. We then have software that will continually check their old email account and download any new mail to our servers.

We did it through a custom script, however i believe a SquirrelMail plugin can do it already, which will probably be easier for you to use.

This allows you to have them setup on your servers, and them still be receiving ALL their email while DNS is still propagating itself, and they only have to check one place for email.

Most (that i know of) Exchange users also allow POP access which will still work with the above SM Plugin.

Answer 2

The reason it has taken some time in the past is most likely due to MX record caching. Right before a move, it's common practice to set the DNS TTL to a low value, such as five minutes or even one minute. If you're going through something like GoDaddy you can change this yourself, or you can ask your hosted DNS provider to change it.

An MX record is the DNS setting for a domain that lets other mail servers know where to send mail. It can be completely separate from the web server (www.example.com), and often is.

http://help.godaddy.com/article/680#mxrecs <-- for GoDaddy specifically

Answer 3

Unfortunately, the transition period for mail transfers is hard to avoid. The only way to avoid it is if the MX record for that domain is pointing at the same host on both sides such as with a Google Apps setup. This is because changing the MX record is a DNS change, and DNS changes can take a long time to fully take hold. Some servers cache records for way longer than the TTL on that record says they should, and that cascades. So when you move MX records, both servers need to be able to correctly receive mail until all traffic switches to the new host.

How hard is it to setup a seperate host for the email and their website, so that I can just leave email alone and only move the website?

This is what the MX DNS record is designed for. It tells mailers which servers at a domain are the servers responsible for receiving mail. This is how mail destined to, say, example.com can be handled by ASPMX.L.GOOGLE.COM instead.