applet "sendmail" remarks

[Brecht Ameije]

On Wed 28 apr 2012 0:27, ralda at gmx.de wrote: 
> 
> Hi !
> 
> > 2nd: "-f sender" option
> > But I've noticed that it's not used!
> 
> > I send mails using:
> >
> > cat header.txt /mnt/jffs2/report-20120404-153857174.csv | busybox
> > sendmail -f testserver at abm.be -S mailserver.abm.be
> >
> > where header.txt contains my from: / to: / subject: lines.
> > I see that the address in the "from:" line in header.txt is used
> > instead of the -f option. And when I leave out the from: line, my
> > outlook client receives an email with an empty "from:" field...
> >
> > Any suggestions?
> 
> The -f option shall set the mail envelope address, which is NOT the "From" in the
> header of your mail! This is a big difference which is got wrong by many users.
> The envelope addresses (sender/recipients) are transmitted during the SMTP
> handshake and usually become not part of the message header. Beside this
> some MTAs/MDAs put envelope addresses in other mail headers (for comment
> purposes), so you may see your envelope addresses if you look closely to all
> your message headers.

Thanks, that's clear. The address from the -f option appears in "Return-Path:" when I check the RAW message. Is there a reason why one would want to use a different address in the "Return-Path" field and in the "FROM" field? 

Brecht

> 
> --
> Harald