Setting Sendmail to Refuse Possibly Forged Headers

Dan Nelson dnelson at
Fri Apr 16 09:53:03 PDT 2004

In the last episode (Apr 16), antenneX said:
> If I may ask one more thing about the milter-sender:
> The only feature I really wanted from the milter was the option to
> control the number of connections for "unknown users". I get a lot of
> those -- dozens -- hundreds. I believe that is called the
> "Rumplestilkin" (sp?) attack where a search is conducted for good
> emails on a system.
> I have not yet seen this option available inside Sendmail and wonder
> if there is one out there yet...?? -- without having to install the
> milter?

There's a confBAD_RCPT_THROTTLE value you can set, which will make
sendmail add 1-second delays between checks after a specified number of
invalid emails, but that's about all you can do from there.

	Dan Nelson
	dnelson at

More information about the freebsd-questions mailing list