sendmail newbie question
m.seaman at infracaninophile.co.uk
Sun Nov 30 01:15:17 PST 2003
On Sat, Nov 29, 2003 at 08:36:57PM -0500, Marty Landman wrote:
[Problems sending mail...]
> In a moment. First I'll say what I do know:
> - there is a /var/mail/Marty, empty
> - emails to Marty go to root's mailbox with the message "user unknown"
> I don't know much. :)
> I did sendmails to localuser at SwamiSalami and Marty at SwamiSalami and this is
> what appended to /var/log/maillog
Try changing your user account to 'marty' -- all lower case. Use
vipw(8) to do that. In general under Unix, usernames are almost
always all lower case and so are most host and domainnames.
The problem is that sendmail(8) [ or any standards compliant MTA ]
expects e-mail addresses to be case insensitive. The DNS copes pretty
well with the host part -- if you look carefully, you'll see that the
FreeBSD mailer uses '... at FreeBSD.org' and '... at freebsd.org' pretty
much interchangeably. In fact, sendmail(8) will always match
domainnames case insensitively, but will preserve the case of any
addresses it processes.
The tricky part is the username -- here sendmail just passes the
username through in whatever case it gets *except* when it does final
delivery (ie. when it passes the message to the local delivery agent).
At that point, it maps the username to lowercase -- for historical
reasons: when sendmail started out there were mail systems that didn't
understand the distinction between lower case and upper case at all,
and the addresses on e-mails passing through those systems would get
case folded. However on unix systems, user 'Marty' is not
automatically the same as user 'marty' or as user 'MARTY'. Such
systems have long since vanished from the net, but I have a sneaking
suspicion that even nowadays some windows mailers may decide that they
"know best" how to capitalise names and will silently "correct" them
It is possible to set up sendmail to preserve the case of usernames
but doing so would mean your mail system wouldn't be standards
compliant, so I'll keep quiet on the issue -- unless anyone really
does have a burning desire to know how?
Dr Matthew J Seaman MA, D.Phil. 26 The Paddocks
PGP: http://www.infracaninophile.co.uk/pgpkey Marlow
Tel: +44 1628 476614 Bucks., SL7 1TH UK
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