Re: What do all these sendmail.mc options mean?

[Dan Nelson]

In the last episode (Feb 24), Jim Johnson said:
> The README file says to add these lines to the sendmail.mc file:
> INPUT_MAIL_FILTER(`spamassassin', `S=local:/var/run/sendmail/spamass.sock, 
> F=, T=C:15m;S:4m;R:4m;E:10m')dnl
> define(`confMILTER_MACROS_CONNECT',`b, j, _, {daemon_name}, {if_name}, 
> {if_addr}')dnl
> 
> However I've found that everything seems to work fine for me if I
> only use the first INPUT_MAIL_FILTER line.  So my questions are:
>
> 1.  What does the INPUT_MAIL_FILTER line do, and what are all those
> crazy options like "C:14m"?

Each INPUT_MAIL_FILTER defines a milter.  If you have multiple ones,
they are called in the order listed.  The extra options tell sendmail
how long to wait for responses, and whether timeouts cause the pending
message to queue or bounce.  They're documented at

http://www.milter.org/milter_api/installation.html

> 2.  What does the confMILTER_MACROS_CONNECT line do?

The MILTER_MACROS_* variables tell sendmail which macro values it is
allowed to send to milters.  Specifically, the "b" macro is what
spamass-milter is looking for.  The rest are sendmail's default values. 
I have no idea why sendmail defaults to just a few permitted macros; I
think it should default to letting milters query any value.

> 3.  Why should or shouldn't I use the confMILTER_MACROS_CONNECT line?

The "b" macro holds the current date in RFC-822 format.  It's not fatal
if spamass-milter can't get the value; the time will just be missing
from the fake "Received:" header sent to spamassassin.  I ask sendmail
for the value instead of just getting the current time myself so that
my "Received:" header is as close as possible to the real header
sendmail will generate if the message is accepted.  The machine running
the milter is not necessarily the same one running sendmail (and
spamassassin may even be running on a third machine), and their clocks
may not be in synch.

-- 
        Dan Nelson
        address@hidden