sympa handing things off to sendmail
we run logcheck on willet and it's seeing some log entries like these
Oct 20 12:17:59 willet postfix/sendmail: warning: -f option specified malformed sender: bounce+ingrese su correo electronico email@example.com Oct 21 05:40:05 willet postfix/sendmail: warning: -f option specified malformed sender: bounce+<theclone==a==hackcanada.com>==firstname.lastname@example.org
Sendmail is choking on that sender, I think probably sympa either needs to escape it somehow or shouldn't be trying to send.
(from redmine: created on 2010-11-15)