On the tahoe-dev mailing list, Zooko suggests:

I really like using the mailing list for patches, because the mailing list is a public, on-the-record conversation that includes everyone.

What about this:

  darcs send -o patch.darcspatch
  bzip2 patch.darcspatch
  darcs diff -u -p"${PATCHRE}" > patch.diff.txt

and then send both to the mailing list as attachments. This is more work for the submitter, as they have to attach the files to a message and send the message (instead of allowing "darcs send" to send the message for them).

The bzip2 is necessary to prevent various mail software from mangling the patch so it can't be applied.

The good things about this are:

• hopefully everyone can see the patch contents in-line in the mail, and
• you can add a "cover letter" -- a message to the mailing list about the patch.