Fixes should be posted to the Bug Tracker
http://sourceforge.net/p/scintilla/bugs/

Features should be posted to the Feature Request Tracker
http://sourceforge.net/p/scintilla/feature-requests/

Either send unified diffs (or patch files) or zip archives with whole files.
Mercurial patch files are best as they include author information and commit
messages.

Questions should go to the scite-interest mailing list
https://groups.google.com/forum/#!forum/scite-interest

Code should follow the guidelines at
http://www.scintilla.org/SciCoding.html

Do not use SourceForge's Merge Request mechanism or message sending
feature as no one is monitoring these.
The neilh @ scintilla.org account receives much spam and is only checked
occasionally. Almost all SciTE mail should go to the mailing list.