[ILUG] Sendmail rules.

[Lars Hecking]

> but can I add a rule to check for a 'Subject' line in an e-mail 
> header and if not present to add an empty 'Subject' line?
 
 a)

 If your local delivery agent is procmail, which is the default on many
 Linux systems, you can just add a recipe to the global procmailrc file,
 /etc/procmailrc. Something like

:0hfw
| /usr/bin/formail -a"Subject:"

 or, if you don't want to run formail on every mail (for performance
 reasons),

:0hfw
* ! ^Subject:
| /usr/bin/formail -a"Subject:"

 b)

 In sendmail.cf, you can add 

HSubject:

 "... to ensure that every mail message has at least an empty Subject: line."

 (quote from bat book). This probably translates to

LOCAL_RULESETS
HSubject:

 in your .mc file.

 But it can get a lot more complicated if you have other local rulesets which
 perform checks on the Subject: header.