Internet Rivers: email
This page lists web sites that are helpful in setting up email on a Linux system.
Sender Policy Framework is a standard that helps webmasters define a email policy for a site (and hopefully reduce spam).
Mailutils is a GNU licensed command line utility for mail. You can install it on ubuntu with: sudo apt-get install mailutils
Mutt E-Mail Client
Mutt is a command line email client.
RoundCube is free open sources software that uses AJAX and the LAMP stack.
Domain Message Authentication Reporting & Conformance
DMARC and SPF and tools developed by paypal and gmail to report on spoofed domains.