Can email and a website for a single domain be hosted separately?

I am about to design a website for somebody, and found a great CMS/host for the site, but they’re already using their domain for their email on a different host (in a different country).

Can I apply only the part of the domain I need to hosting the website, while letting their email host remain doing their thing, or does it always come in a package deal; i.e. cue major swapover hassle?

Yes. Email is routed to the MX record for the domain. That record is independent of the main zone record and any subdomains you may define.

Here are instructions on how and where to change MX records:

http://www.google.com/support/a/bin/answer.py?answer=33352
(these instructions are specific to switching to Google Apps for Mail, but it will give you a good idea of what to do. Use the same steps, except use the mail server address for your specific host)

I don’t want to change the MX Records, they’re the part that ought to remain as the status quo. I want to apply the, thus far unused, website part, which I assume is HTTP or some such.

I trust friedo’s information, so I will continue as planned.

Thanks.

Yeah, what friedo says is right.

Depending on your setup, you need to change your records from the control panel of your domain registrar/host. Set the A record to your new website host.

For example, the DNS servers will point to your existing domain registrar or host:

ns1.yourdomainhost.com
ns2.yourdomainhost.com
ns3.yourdomainhost.com

The MX records will point to your existing host.

And your A records should be changed to point to your new website host.

e.g.

A Record entries:

DOMAIN | IP ADDRESS
yourdomain.com | XX.XX.XX.XX
www.yourdomain.com | XX.XX.XX.XX
subdomain.yourdomain.com | XX.XX.XX.XX

If you need step-by-step instructions, let us know.