Before you sit down to write from scratch that e-mail program your boss has been pestering you about, consider starting with one of the several freely available working sample programs. There's a whole gaggle of them, and they appear below in alphabetical order:

Aaron Bartell's RPGMail Utility
This is an RPG service program that interfaces with Sun's JavaMail APIs.
http://mowyourlawn.com/html/RPGMail.html

Genesis V's Email Utility
This utility includes the CMD, CL, and RPG source, along with installation instructions.
http://www.genesisv.com/freesource/email.shtml .

IBM article "Mail Enabling AS/400 Applications with Java"
http://www-919.ibm.com/developer/java/topics/javamail.html

IBM article "iSeries-Based E-mail Processing Applications with Java"
http://www-919.ibm.com/developer/java/topics/mailproc.html

IBM's Easy400 iSeries MIME & MAIL Utility
This utility enables you to create and send Multipurpose Internet Mail Extensions (MIME) e-mail. The utility includes an address book and distribution list that you can use to send e-mails. All source is included in the download, and the site includes a tutorial and links for more information.
http://www.easy400.ibm.it/mmail/start

iSeries NEWS Utility SNDEMAIL
This utility was published in the September 1998 iSeries NEWS article "RPG Utility Puts QtmmSendMail API to Work," which can be viewed and downloaded by iSeries Professional members.
http://www.iseriesnetwork.com/article.cfm?ID=2806

Uzaemon'sSend SMTP Mail (SNDM)
This enables you to send an e-mail from an iSeries command line or CL program. The complete source and installation instructions are included. http://homepage1.nifty.com/uzaemon/#download