Re: mail headers - why do they differ?
On Sat, Oct 13, 2001 at 07:51:21AM +1000, Sam Varghese wrote:
> I was looking at the Debian mailing list archives
> for some info this morning and came across one
> of my old postings. The headers read as under:
>
> To: debian-user@lists.debian.org
> Subject: exim problem - rejecting senders
> From: Sam Varghese <sam@gnubies.com>
This one is likely the result of your muttrc, but..
> Date: Sun, 30 Sep 2001 15:15:36 +1000
> Mail-Followup-To: debian-user@lists.debian.org
> Sender: Sam Varghese <samuel@gnubies.com>
..this one is probably added by Exim.
It's very easy to forge From-addresses in email, that's what the line
Sender = "Sam Varghese <sam@gnubies.com>"
in your ~/.muttrc files tell mutt to do. Most MUA (mail user agents)
allow such things. But fortunately most sane MTA (mail transport
agents) fix this by adding a true Sender header. This seems a catch
42, but Linux wouldn't be unix if there wasn't a way out:) Either add
the user samuel to Exim's trusted users list (which would allow samuel
to forge the From header amongst other things, so NOT recommended) or
use Exim's powerfull header rewriting trickery or login as sam.
I prefer to rewrite headers in such cases, look at the section
"Address rewriting" in Exim's info files. The trouble with older
exim's (the one in potato) is that the rewriting is a global thing.
Newer exim's allow to specify rewriting rules per transport. You can
easily fake your own special cased rewriting rules per transport for
older versions by having the transport go through a pipe, and in that
pipe have a sed call to do the tranformations you need.
> True, I log in to my workstation as samuel - should I
> change this to sam? ..................................
no, why should you?
> ................... And would it suffice to change the
> username in /etc/passwd and /etc/shadow and then reboot?
you should fix /etc/group and /etc/sgroup too. And forget about
rebooting, just login afresh if that makes you feel better.
--
groetjes, carel
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