qpsmtpd is a flexible smtpd daemon written in Perl. Apart from the core SMTP features, all functionality is implemented in small "extension plugins" using the easy-to-use object oriented plugin API. qpsmtpd was originally written as a drop-in qmail-smtpd replacement, but now it also includes an smtp forward and a postfix "backend".
Hailo is a fast and lightweight markov engine intended to replace AI::MegaHAL. It has a Mouse (or Moose) based core with pluggable storage, tokenizer, and engine backends. It is similar to MegaHAL in functionality. The main differences (with the default backends) are better scalability, drastically less memory usage, an improved tokenizer, and tidier output. With this distribution, you can create, modify, and query Hailo brains. To use Hailo in event-driven POE applications, you can use the POE::Component::Hailo wrapper. One example is POE::Component::IRC::Plugin::Hailo, which implements an IRC chat bot.
Net::DRI is an object-oriented Perl library with a uniform API to access services from domain name registries/registrars/resellers. With protocols (RRI, RRP, EPP, and XCP), it handles EU, BE, SE, PL, WS, MOBI, AERO, CAT, US, COM, NET, ORG, BIZ, INFO, COOP, LU, AT, FR, NAME, NU, ASIA, TV, CC, AU, UK, NO, DE, CH, LI, HN, SC, VC, AG, BZ, LC, MN, ME, CZ, TRAVEL, PRO, JOBS, BR, PT, SI, IM, IT, CO.CZ, TC, VG, GD, NL, AU, CA, GL, CentralNIC, and CoCCA, all with extensions. It can also perform Whois queries, domain availability checks (DAS), ENUM registrations (IENUM +43) and validations, IRIS DCHK (RFC 3981 and 5144) for .DE, and operations through the APIs of BookMyName, OVH, Gandi, AdamsNames, and OpenSRS. It also includes a shell to leverage all its power without a single line of code. It has a flexible and robust logging framework, and handles internationalization issues, DNSSEC, and IPv6.
Apache SpamAssassin is an extensible email filter that is used to identify spam. Once identified, the mail can then be optionally tagged as spam for later filtering. It provides a command line tool to perform filtering, a client-server system to filter large volumes of mail, and Mail::SpamAssassin, a set of Perl modules allowing Apache SpamAssassin to be used in a wide variety of email systems.
Carp::Clan is a module that reports errors from the perspective of the caller of a "clan" of modules, similar to "Carp.pm" itself. Instead of giving it a number of levels to skip on the calling stack, you give it a pattern to characterize the package names of the "clan" of modules which shall never be blamed for any error. These modules stick together like a "clan" and any error that occurs will be blamed on the "outsider" script or modules not belonging to this "clan".