Perl5 compression modules (bzip2, deflate, gzip, zlib, zip)

https://metacpan.org/release/IO-Compress

IO::Multiplex - Manage IO on many file handles

https://metacpan.org/release/IO-Multiplex

Supporting module for SOAP::Lite

http://search.cpan.org/dist/IO-SessionData/

Perl module with object interface to AF_INET6 domain sockets

https://metacpan.org/release/IO-Socket-INET6

Drop-in replacement for IO::Socket::INET supporting IPv4 and IPv6

https://metacpan.org/release/IO-Socket-IP

Simplified Perl5 module to handle I/O on in-core strings

https://metacpan.org/release/IO-String

Flexible I/O Perl5 module that allows manipulation of pseudo-TTYs

http://search.cpan.org/dist/IO-Tty/

IO:: style interface to Compress::Zlib

https://metacpan.org/release/IO-Zlib

Use IO handles with non-file objects

https://metacpan.org/release/IO-stringy

Fast lookup of country codes from IP addresses

https://metacpan.org/release/IP-Country

Run subprocesses with piping and redirection

https://metacpan.org/release/IPC-Run

Simple interface to access shared memory

https://metacpan.org/release/IPC-ShareLite

IPC::Signal - Utility functions dealing with signals

https://metacpan.org/release/IPC-Signal

Database connection caching and organization

https://metacpan.org/release/Ima-DBI

Perl module for getting image information

https://metacpan.org/release/Image-Info

Helper functions for PBM/PGM/PPM image file formats

https://metacpan.org/release/Image-PBMlib

Perl5 module to determine the size of images in several common formats

https://metacpan.org/release/Image-Size

Perl extension to convert to JSON (JavaScript Object Notation)

https://metacpan.org/release/JSON

Perl Wrapper Class for the various JSON classes

https://metacpan.org/release/JSON-Any

JSON::XS compatible pure-Perl module

https://metacpan.org/release/JSON-PP

JSON serialising/deserialising, done correctly and fast

https://metacpan.org/release/JSON-XS

Perl extension interface to convert Japanese text

https://metacpan.org/release/Jcode

Guess media type for a file or a URL

https://metacpan.org/release/LWP-MediaTypes

Combines List::Util and List::MoreUtils in one bite-sized package

https://metacpan.org/release/List-AllUtils

Perl extension for comparing lists

https://metacpan.org/release/List-Compare

Provide the stuff missing in List::Util

https://metacpan.org/release/List-MoreUtils

Message handling functions

https://metacpan.org/release/gettext

Perl extension to bring loggers and listeners together

https://metacpan.org/release/Log-Any

Log4j implementation for Perl

http://log4perl.com

Perl5 module for Base32 encodings

https://metacpan.org/release/MIME-Base32

Perl5 module for Base64 and Quoted-Printable encodings

https://metacpan.org/release/MIME-Base64

Simple interface for creating (not parsing!) MIME messages

https://metacpan.org/release/MIME-Lite

Set of perl5 modules for MIME

https://metacpan.org/release/MIME-tools

Perl extension for determining MIME types

https://metacpan.org/release/MIME-Types

Store multi-level hash structure in single level tied hash

https://metacpan.org/release/MLDBM

MLDBM::Sync - safe concurrent access to MLDBM databases

http://search.cpan.org/dist/MLDBM-Sync/

Add mro::* interface compatibility for Perls < 5.9.5

https://metacpan.org/release/MRO-Compat

Perl5 module to process and/or create DKIM email

http://jason.long.name/dkimproxy/

Perl implementation of DomainKeys

https://metacpan.org/release/Mail-DomainKeys

Reference implementation of the RFC 4408 SPF protocol

https://metacpan.org/release/Mail-SPF

Query Sender Permitted From for an IP,email,helo

http://spf.pobox.com

Perl module implementing a simple, platform-independent mailer

http://search.cpan.org/dist/Mail-Sendmail/

Perl5 modules for dealing with Internet e-mail messages

http://search.cpan.org/dist/MailTools/

Encoding and decoding of base36 strings

https://metacpan.org/release/Math-Base36

Arbitrary size integer math perl package

https://metacpan.org/release/Math-BigInt

Arbitrary big rational numbers

https://metacpan.org/release/Math-BigRat

Perl extension for rounding numbers

https://metacpan.org/release/Math-Round

Build and install Perl modules

https://metacpan.org/release/Module-Build

Lets you find and use modules in categories

http://search.cpan.org/dist/Module-Find/

Loads one of several alternate underlying implementations for a module

https://metacpan.org/release/Module-Implementation