Appendix B: Related Packages

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Qmail is a complete Mail Transfer Agent (MTA), but many packages were either designed specifically to add new functionality to qmail or simply work well with qmail. This appendix lists some of these packages, describes them briefly, and provides links for more information.

The unofficial qmail home page, http://www.qmail.org/, is the definitive collection of information about qmail-related packages.

checkpassword

checkpassword is the authentication package used by qmail-pop3d (really qmail-popup). The standard checkpassword package by Daniel Bernstein (http://cr.yp.to/checkpwd.html) authenticates users with the Unix password file.

Many alternative checkpassword implementations support other authentication mechanisms including Lightweight Directory Access Protocol (LDAP), Structured Query Language (SQL) databases, Pluggable Authentication Modules (PAM), Authenticated POP (APOP), and dedicated POP password files. The unofficial qmail home page contains a checkpassword section with links to these alternative implementations (http://www.qmail.org/top.html#checkpassword).

Tip 

To verify that your checkpassword program is authenticating properly, you can test it from the command line using Perl. For example, if user paul's password is Lauren&Natalie, the command perl -e 'printf "%s\0%s\099\0", "paul", "Lauren&Natalie"' | /bin/checkpassword echo OK 3<&0 will output "OK" if the authentication succeeds and nothing if it fails.

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