tMTA is a miniature Mail Transport Agent that vaguely emulates the command-line interface of Sendmail as used by many Unix programs such as mail(1). tMTA only supports local delivery to local users. It does not support SMTP or any form of inter-computer mail transport. It provides the barest functionality for daemons and users on a computer to communicate with each other using the common mail interface.
queue_repair can be used to check or correct most corruptions of the queue in qmail (resulting from filesystem damage, etc). Functionality includes automatic, dynamic determination of UIDs and GIDs. Automatic, dynamic determination of use of big-todo. Handles basic tasks like fixing a queue restored from backups, incorrect ownership or permissions of directories and files, missing or extra split subdirectories, unexpected files or other directories, or creating a valid queue from scratch.
Whoson (WHO iS ONline) is a proposed Internet protocol that allows Internet server programs know if a particular (dynamically allocated) IP address is currently allocated to a known (trusted) user and, optionally, the identity of the said user. The protocol could be used by an SMTP Message Transfer System in conjunction with anti-spam-relaying filters to implement a scheme similar to the one described here to allow roaming customers use their "home" SMTP server to submit email while connected from a "foreign" network.
QUICA is a Web interface to manage various aspects of email administration. Working as a courier-mta frontend, it can make a quick and easy to use email server. Tasks like creating accounts and forwards can be done easily. It manages domains separately, allowing the delegation of each domain to different people. It's a great tool for your customers if you are a service provider, but also works well for a single domain. Quotas for each account are managed, the number of email messages and hard disk space can be controlled accurately. Internationalization is provided (with some languages included) and you can add your own. The interface allows you to delegate the management to non-sysadmins.
Arb-Scan is a remote banner scanner written in bash and Perl. It supports 12 different services banner checks (daytime, ftpd, sshd, smtpd, domain, finger, httpd, pop2, pop3, nntp, imapd and snpp). It features IP file reading, logging, random IP scanning, ftp anonymous login checking and VRFY/EXPN smtp checking.