This article is a part of a series describing the installation of Microsoft Office SharePoint Server 2007 (MOSS) on a Windows Server 2008 with the newly released SQL Server 2008. If you have deployed your environment using a Windows Server 2003 Active Directory you can use the mail service from Windows Server 2003.
Update: 60 min - Install SharePoint with PowerShell easy and fast
Please have a look at
Hmm, where was that POP3 server role? Or was it a feature?
It doesn't exist any more... POP3 has been deprecated and is no longer part of Windows Server.
You have to use an alternative like to Install Microsoft Exchange Server 2007 or something from the cloud... (Did I say that loud?)