With Sympa 6.2.24 and later, Sympa Administration Manual was provided on new documentation site.
With Sympa through 5.3.x to 6.2.16, Reference Manual was provided as wiki site using DokuWiki. Some versions have PDF format (See above).
With Sympa 5.2.x or earlier, the manual was bundled in source distribution as TeX sources. To get them, see repository of historical releases.