I recently mailed to the tracker a mail containing
---
lines (to mark up code snippets), but the mail gateway
removed everything below it.

Looking into the code I find the pattern for the
signature to be
signature=re.compile(r'^[>|\s]*[-_]+\s*$')

(mailgw.py, line 1111),

and I'm wondering why that doesn't simply read

 signature=re.compile(r'^-- $').

As far as I know, it's really '--' that should be
matched, not any number of '-' greater than 1.

Logged In: YES 
user_id=469548

Fixed on HEAD.