Mail Indexers:

Stuff related to Indexing and Searching. Besides Spotlight, of course.

• Zoë - self-containted Java-based mail archiver and indexer. Requirers duplicating or migrating your mail store, eats RAM and disk like there's no tomorrow. Dated interface.
• mairix - simple, neat, effective if somewhat limited (does not index attachments)

• Namazu - C/Perl hybrid (format parsers are in Perl). Supports Japanese encodings.
• Lucene - Java-based, powers several different search applications and has spawned countless ports to other languages:
  • Lucene4c - for C
  • CLucene - for C++
  • PyLucene - compiled Java with SWIG bindings to Python
  • Lupy - native Python port