getmail is intended as a simple, secure, and reliable replacement for fetchmail. It retrieves email (either all messages, or only unread messages) from one or more POP3, SPDS, or IMAP4 servers (with or without SSL) for one or more email accounts, and reliably delivers into qmail-style Maildirs, mboxrd files, or through external MDAs (command deliveries) specified on a per-account basis. getmail also has excellent support for domain (multidrop) mailboxes, including delivering messages to different users or destinations based on the envelope recipient address.
mxCrypto is an extension package that provides OO-style access to the cipher algorithms and hash functions included in OpenSSL/SSLeay, a very nifty cryptographic library originally written by Eric Young and now maintained by the OpenSSL team. Its main purpose is filling in the missing parts in Andrew Kuchling's pycrypt export package with high quality implementations. Due to the ITAR export restrictions on cryptographic software, Andrew's implementations are not legally downloadable from outside the US.
python-ldap provides an object-oriented API to access LDAP directory servers from Python programs. Mainly, it wraps the OpenLDAP 2.3+ libs for that purpose. Additionally, the package contains modules for other LDAP-related stuff (such as processing LDIF, LDAPURLs, and LDAPv3 schema).
dnspython is a DNS toolkit for Python. It supports almost all of the record types. It can be used for queries, zone transfers, and dynamic updates. It supports TSIG authenticated messages and EDNS0. dnspython provides both high and low level access to DNS. The high level classes perform queries for data of a given name, type, and class, and return an answer set. The low level classes allow direct manipulation of DNS zones, messages, names, and records.
pywrat (Python Wrappers for Remote Access Tools) is a set of wrappers that can be used for accessing remote hosts. They use ssh and scp for remote shell and file system access and can be used as a generalized access method with a single configuration file for all host, user, and key setups. The wrappers are intended to simplify remote access in shell scripts, but it is also possible to use the wrapper modules directly from Python programs.
Construct is a Python library for declaratively defined data structures, called "constructs". These constructs can both parse data into an object and build an object into data. Constructs handle fields of either byte or bit granularity, structs, unions, sequences, repeaters, adapters, validators, switching, pointers, on-demand (lazy) parsing, and many more. The library defines a large number of primitive constructs, as well a large inventory of file formats and network protocols.