and a mail host alias of mail.cshore.com, can't hurt

>The actual hostname is "mail.cshore.com" in DNS.

Two different names and functions. Call it the DNS hostname whatever you want in whatever domain you want.

>In appears that users have a reply address of "username@cshore.com" >BUT can log in with "username" only. >I'm not running IIS on the box so I have changed the port for webmail to >"80". So users can check their mail http://mail.cshore.com and just type in >their username, without the "@domain.com"

why not call it something more articulate:

@ MX mx2000.cshore.com. ; mail servers send mail here ; for the 2000 users. mail MX mx2000.cshore.com. ; ditto ; pop A ip.ad.re.ss ; 2000 users read mail here smtp A ip.ad.re.ss ; 2000 users send mail here webmail A ip.ad.re.xx ; 2000 users do webmail here

>I will only run a single domain on this box.

That's the only way you can drop the fully qualified login, without @domain.com. All virtuals need the fully qualified account name.

>I'm just double checking so the >move goes without any problems. Does anyone see any potential problems ?

no. Before the switch, reduce your TTL on that zone from 1d to 1h, let a day pass to less cached records expire, do the switch, raise the TTL to 1d.

Len