diagnosing smail

[kotsya@u.washington.edu (David Stern)]

Hi,

I'm trying to beat smail down with a stick, am having a little trouble 
(actually more than a little).  Would somebody *PLease* translate into 
English this brief /etc/smail/config snippet and answer three questions?

  from_field="From: \
      ${if def:ident_sender\
      {$ident_sender@$visible_name}\
      {$sender${if def:sender_name: ($sender_name)}}}"

(My interpretation: "look at the From: line (or Sender: line, which?), 
and if the sender's "identification code" (whatever that means) is 
non-null (exists), then rewrite that line (which one: From: or Sender: 
?) to look like .. here it breaks down, and that extra condition in the 
last line confuses me.)

1.) What is the difference between the roles of Sender:, Return-path:, 
and From: lines and are each required according to RFC's?  (It was my 
understanding that there was some contention as to whether the Sender: 
line was required, but that it was desirable because it acts as an 
"envelope", which is a good thing for some MTA's and MUA's.  I'm not 
clear about the roles of Return-path:, From:, and Sender: or which are 
required.)

2.) Why does "from_field" require it begin "From:" (as shown in the man 
page below) and does "from_field" rewrite the "From:" line, or the 
"Sender:" line and how does it decide? (It seems ambiguous.)

8<------------------- man smailconf(5) --------------------->8

  from_field
    type: string
    
    This string will be expanded to form From: or Sender:
    fields. The expanded string must begin with "From:", 
    which may be replaced by other strings to form an   
    actual header field. The default value is:

      From: $sender${if def:sender_name: ($sender_name)}

8<---------------------------------------------------------->8

3.) How can I find out what ident_sender, as well as all other 
variables, are assigneded as?  (I need to know so I can test what is 
happening; e.g.: when I set visible_name to u.washington.edu, and 
restart smail and inetd or reboot, there is no change, but I don't know 
why. I've tried echoing and mailing the variables, but I must be doing 
it wrong.)

I know smail is reading my configuration because smtprewrite is being 
implemented, and modifying transports to remove and insert headers 
works, yet my attempts to modify /etc/smail/config have mostly been 
futile.
-- 
David Stern                          
------------------------------------------------------------------
                             http://weber.u.washington.edu/~kotsya
                                           kotsya@u.washington.edu




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