There are two things that can go seriously wrong when you move to a new web hosting provider. Follow this simple guide to doing it all without too many dramas.
A normal move to a new hosting provider can mean huge losses to your business if things aren't done correctly. Specifically:
1. Your new web site doesn't "behave" the way it should.
2. Your email goes "missing" for several days
SETTING UP THE NEW SERVER
Setting up the new server correctly easily solves the first problem.
Set up the new server with your existing/main domain name details (but do NOT change the DNS settings - yet).
Once the server is set up, you can then PARK another/spare domain name at the same server.
For example, most servers with cPanel allow you to easily park one - or more - domains on top of an existing one. If you don't happen to have a spare/unused domain name you can use for this purpose, it won't cost much to register a new .com just for this purpose.
Now, make sure that the DNS information for the PARKED domain at your domain name registry points to the new server.
Once you can see your web site under the parrkeddomainname.com address in your web browser, FULLY TEST IT to make sure all the interactive routines - i.e. search routines, contact forms, forums, feeds, etc., work as they should.
Once you are 100% certain that it works properly, AND you've got your email sorted out (see next bit) then you can organize to have the DNS for your main domain name changed to point to the new server.
BIG TIP: Make a small change to the NEW home page so you can easily tell which site (old or new) you are looking at in your web browser. When you can see the change, it means your DNS has been updated.
DON'T LOSE ANY EMAIL
The problem with a DNS change is that it can take some time to go through - up to 72 hours or even longer for it to propagate across the whole Internet.
During that time, some of your customers will be seeing the OLD version of your site, and if they send you email, it can be delivered to the OLD server.
And you might not be able to check it because your ISP has updated the DNS and you can only see the new server.
AT THE OLD SERVER, simply set up a FORWARD or REDIRECTION to send all your mail to your existing ISP email account, or perhaps even a new Hotmail type address.
For the final time, in Outlook (or whatever email client you use) click on Send/Receive to get any mail that might be waiting on the old server. After this new email (to your old server) will come in through your ISP email box.
Next, set up your email accounts AT THE NEW SERVER. You should ALSO set up redirects here to send any mail it receives to your ISP address. That way, if you're unlucky and your DNS takes forever to propagate, you will still get your new email.
Finally, when you are all ready to go, lodge the DNS change with your domain name registrar to point your main domain to the new server.
WHILE THE DNS IS UPDATING
If everything's been set up correctly, then while the DNS is updating, several things will happen:
1. Any email being sent to the old server will be redirected to your ISP email address.
2. Any email that's sent to the NEW server is ALSO being redirected to your ISP address, so you won't lose any email during this period.
3. Your email client should keep checking the old server until the DNS change goes through. When that happens, it will most likely display an "unable to connect" error message.
4. Now, check to make sure you can see your new server in your web browser.
5. If you can, then change your email settings to the new server settings and check it works both sending and receiving.
6. Now remove the redirections from the new server.
Finally, in about another week or so, contact your OLD hosting provider and CLOSE YOUR ACCOUNT. It's an important step, but so many people forget to do it, until they get re-billed for another month (and lot's of luck trying to get a refund).