Index: tools/hook-scripts/mailer/mailer.py
===================================================================
--- tools/hook-scripts/mailer/mailer.py	(revision 1438886)
+++ tools/hook-scripts/mailer/mailer.py	(working copy)
@@ -98,7 +98,7 @@ def main(pool, cmd, config_fname, repos_dir, cmd_a
   if cmd == 'commit':
     revision = int(cmd_args[0])
     repos = Repository(repos_dir, revision, pool)
-    cfg = Config(config_fname, repos, { 'author' : repos.author })
+    cfg = Config(config_fname, repos, { 'author' : repos.author, 'repodir' : os.path.basename(repos.repos_dir) })
     messenger = Commit(pool, cfg, repos)
   elif cmd == 'propchange' or cmd == 'propchange2':
     revision = int(cmd_args[0])
@@ -108,14 +108,14 @@ def main(pool, cmd, config_fname, repos_dir, cmd_a
     repos = Repository(repos_dir, revision, pool)
     # Override the repos revision author with the author of the propchange
     repos.author = author
-    cfg = Config(config_fname, repos, { 'author' : author })
+    cfg = Config(config_fname, repos, { 'author' : author, 'repodir' : os.path.basename(repos.repos_dir) })
     messenger = PropChange(pool, cfg, repos, author, propname, action)
   elif cmd == 'lock' or cmd == 'unlock':
     author = cmd_args[0]
     repos = Repository(repos_dir, 0, pool) ### any old revision will do
     # Override the repos revision author with the author of the lock/unlock
     repos.author = author
-    cfg = Config(config_fname, repos, { 'author' : author })
+    cfg = Config(config_fname, repos, { 'author' : author, 'repodir' : os.path.basename(repos.repos_dir) })
     messenger = Lock(pool, cfg, repos, author, cmd == 'lock')
   else:
     raise UnknownSubcommand(cmd)
Index: tools/hook-scripts/mailer/mailer.conf.example
===================================================================
--- tools/hook-scripts/mailer/mailer.conf.example	(revision 1438886)
+++ tools/hook-scripts/mailer/mailer.conf.example	(working copy)
@@ -146,7 +146,16 @@
 #
 #   from_addr = %(author)s@example.com
 #
+# The substitution variable "repodir" is provided, and is set to
+# the directory name of the repository. This can be useful to set
+# a custom subject that can be re-used in multiple repositories:
 #
+#   commit_subject_prefix = [svn-%(repodir)s]
+#
+# For example if the repository is at /path/to/repo/project-x then
+# the subject of commit emails will be prefixed with [svn-project-x]
+#
+#
 # SUMMARY
 #
 # While mailer.py will work to minimize the number of mail messages