[NTLUG:Discuss] Sendmail question

[Eric Schnoebelen]

Kelledin writes:
- On Monday 27 May 2002 03:31 pm, you wrote:
- > I'm a newbie so please go easy on me...  Recently downloaded,
- > burned and installed a copy of RH 7.3 on a Dell PowerEdge 4200
- > server.  I am wanting this box to handle email for a domain
- > hosted elsewhere (http://www.richardsonhumanesociety.com).  Is
- > this possible?

- Yes, using your static IP.  Every domain name in a DNS table is
- required to have an "A" record (to determine which IP address(es)
- to associate with this domain name); each domain name may also
- have an "MX" record (to determine the IP address(es) of the SMTP
- server for this domain).  You just need to set up the SMTP server,
- then contact whoever is maintaining the master DNS servers for
- your domain name (assuming you aren't maintaining them yourself)
- and have them commit the change.

	Some incorrect information needs to be corrected here.

	A DNS zone _must_ have only two records, the SOA, and
the NS records.  An A record is not required, and frequently,
not desired.

	For the case above, an MX record at the zone level is
all that is required to route mail to the new server. However,
the MX record _MUST_ contain the fully qualified domain name of
the system that is going to accept the mail.  That system does
not need to be in the same domain.  The MX record _must_not_
contain an dotted-quad IP address (that is a violation of the
DNS spec, and will cause some mail servers not to deliver to
you.)

	Since the DNS is probably hosted somewhere else, you'll
need to have the DNS hosting company add the MX pointing at your
server.

	FYI: it looks like richardsonhumanesociety.com already
has two mail handlers defined...

- > If so, for someone who knows nothing about sendmail and very
- > little about Linux (or any other Unix-like environment), how
- > difficult is the challenge?
- 
- This can be done, but sendmail is not for beginners.  You might
- be better off with an alternative SMTP server like postfix.

	In this case, sendmail is no easier or harder that
postfix or qmail to configure.  In sendmail's case, add the new
domain(s) to /etc/mail/sendmail.cw, or
/etc/mail/local-host-names (depending upon the distribution) and
restart sendmail.  Any mail destined for the hosts/domains listed in
those files will be accepted for local delivery.

	(it sounds like several people on this list have fallen
for the myth that sendmail is hard to configure.  That hasn't
been true for many a year... Having attempted to configure both
sendmail and qmail, I find sendmail much easier.)

- You'll also need to know how to set up the necessary port forwarding
- on your router.

	Yes, you'll need to make sure the SMTP port is open on
your firewall.

- > What I would like to do is be able to assign user mail accounts
- > which members can check through their respective email clients
- > if possible.
- 
- This is simple enough, but an SMTP server like sendmail is only
- part of the solution.  You'll also need a POP/IMAP server set
- up.  The SMTP server takes care of receiving and storing mail;
- the POP/IMAP server allows e-mail clients to download messages
- stored by sendmail.

	True enough.  QPOPPER or UW-IMAP will play extremely
well with the stock sendmail configurations, using mailboxes in
/var/mail.  This _will_ require all your users to have accounts
on the system, but you can give them a shell of /bin/false, or
/bin/passwd, so they can't actually log in.

--
Eric Schnoebelen		eric at cirr.com		http://www.cirr.com
  "I came out of it dead broke, without a house, without anything except a
   girlfriend and a knowledge of Unix." "Well, that's something. Normally
     those two are mutually exclusive" - Neal Stephenson, Cryptonomicon