Forums Scripts & Popups Targeting text within key identifiers

I'd like to strip names and domains out of a flat file database with the following "exact format" and place the "names" and "domains" into separate files. All help is valued.

email:johnathonthames@bridgeportnews.com
email:corrykalb@signgraphics.com
email:jessicarhodes@scienceargifarms.com
email:joshcohen@milltonpifer.com

ie,

-------- users.txt (johnathonthames)
|
database file (email:johnathonthames@bridgeportnews.com)
|
-------- domains.txt (bridgeportnews.com)