nLab categories mailing list

The Categories mailing list is a mailing list on the topic of category theory.

The list commenced in 1990 and is still (somewhat) active. From 1990 to 2023, the mailing list was hosted by Mount Allison University ( and moderated by Bob Rosebrugh. In 2023, the mailing list was transitioned to Macquarie University ( and is currently moderated by Jean-Simon Lemay.

The journal Theory and Applications of Categories was launched on the mailing list in January 1995.


The list’s messages are archived in a number of different ways, depending on date:

  • For June 1994 to November 1999, there is a curated website, organised alphabetically by topic/title:

  • For 11 March 1990 (the start) to July 2009 (when a change in Outlook led to a halt in archiving), there are compiled monthly digests, organised in yearly/monthly folders here:

  • An dump of the Gmane archive (otherwise only accessible via the protocol nntp) can be found on GitHub, which is searchable, but not sorted or archived in any particularly human-readable way.

The website for the old categories mailing list (

See also

Last revised on October 23, 2023 at 12:14:34. See the history of this page for a list of all contributions to it.