The IO::Zlib module is a Perl IO style interface to Compress:Zlib that simplifies reading and writing compressed data.

This package provides PGPLOT bindings for Perl. It uses giza instead of PGPLOT for the implementation, though.

The Math::Cephes module provides a Perl interface to over 150 functions of the Cephes math library.

This package provides a library and simple REPL for the Perl Data Language.

This package provides the Math::MatrixReal module. It implements the data type "matrix of real numbers" (and consequently also "vector of real numbers").

This package provides a library and simple REPL for the Perl Data Language.

This package provides modules to do 3D graphics in PDL.

This packages allows you to interpolate the value Y from X using a list of (X, Y) pairs.

This module implements a wrapper for Net::SMTP, enabling over-SSL/STARTTLS support. This module inherits most of all the methods from Net::SMTP(2.X).

This module defines a format for database URIs, and provides a URI class to handle these.

WWW::Pastebin::PastebinCom::Create provides functionality to paste on Pastebin without API keys.

This package provides a HTML and XML DOM parser. It also supports CSS selectors.

The Perl module Geo::IP looks up location and network information by IP Address.

This module provides functions to deal with IPv4/IPv6 addresses. The module can be used as a class, allowing the user to instantiate IP objects, which can be single IP addresses, prefixes, or ranges of addresses. There is also a procedural way of accessing most of the functions. Most subroutines can take either IPv4 or IPv6 addresses transparently.

This module is a suite of tools for implementing DMARC. It adheres to the 2013 DMARC draft, intending to implement every MUST and every SHOULD.

The package provides bindings for GNU Libidn, a C library for handling Internationalized Domain Names according to IDNA (RFC 3490), in a way very much inspired by Turbo Fredriksson's PHP-IDN.

Apache SpamAssassin is an anti-spam platform giving system administrators a filter to classify email and block spam (unsolicited bulk email). It uses a robust scoring framework and plug-ins to integrate a wide range of advanced heuristic and statistical analysis tests on email headers and body text including text analysis, Bayesian filtering, DNS blocklists, and collaborative filtering databases.

This package provides an old GeoIP database in the legacy .dat format. The data was collected before MaxMind changed the license and format of their databases. It is intended only as a compatibility package for SpamAssassin.

This module looks up the Gravatar for any email address by constructing a URL to get the image from gravatar.com. A Gravatar is a Globally Recognized Avatar for a given email address. This allows you to have a global picture associated with your email address.

This module provides functions to percent-encode and percent-decode URI strings as defined by RFC 3986. Percent-encoding URI's is informally called URI escaping. This is the terminology used by this module, which predates the formalization of the terms by the RFC by several years.

URI::Nested provides support for nested URIs, where the scheme is a prefix, and the remainder of the URI is another URI.

This package provides a class method constructs a new Net::IMAP::Simple object. It takes one required parameter which is the server to connect to, and additional optional parameters.

This package provides a client library for Vipul's Razor. Vipul's Razor is a distributed, collaborative, spam detection and filtering network. Through user contribution, Razor establishes a distributed and constantly updating catalogue of spam in propagation that is consulted by email clients to filter out known spam. Detection is done with statistical and randomized signatures that efficiently spot mutating spam content. User input is validated through reputation assignments based on consensus on report and revoke assertions which in turn is used for computing confidence values associated with individual signatures.

Back in the early days of the web, many people learned Perl because of a wonderful Perl library called CGI. It was simple enough to get started without knowing much about the language and powerful enough to keep you going, learning by doing was much fun. While most of the techniques used are outdated now, the idea behind it is not. Mojolicious is a new endeavor to implement this idea using modern technologies.