This section covers more involved topics such as mail configuration and setting up mail for an entire domain.
Out of the box, one can send email to external hosts as
long as /etc/resolv.conf
is configured or
the network has access to a configured
DNS server. If order to have mail
delivered to the MTA on the FreeBSD host,
do one of the following:
Run a DNS server for the domain.
Get mail delivered directly to to the FQDN for the machine.
In order to have mail delivered directly to a host, it must have a permanent static IP address, not a dynamic IP address. If the system is behind a firewall, it must be configured to allow SMTP traffic. To receive mail directly at a host, one of these two must be configured:
Either of the above will allow mail to be received directly at the host.
Try this:
#
hostname
example.FreeBSD.org
#
host example.FreeBSD.org
example.FreeBSD.org has address 204.216.27.XXIn this example, mail sent directly to <yourlogin@example.FreeBSD.org>
should work without problems, assuming
Sendmail is running correctly on
example.FreeBSD.org
.
For this example:
#
host example.FreeBSD.org
example.FreeBSD.org has address 204.216.27.XX
example.FreeBSD.org mail is handled (pri=10) by hub.FreeBSD.orgAll mail sent to example.FreeBSD.org
will be
collected on hub
under the same username
instead of being sent directly to your host.
The above information is handled by the DNS server. The DNS record that carries mail routing information is the MX entry. If no MX record exists, mail will be delivered directly to the host by way of its IP address.
The MX entry for freefall.FreeBSD.org
at one time looked
like this:
freefall
had many MX
entries. The lowest MX number is the host
that receives mail directly, if available. If it is not
accessible for some reason, the next lower-numbered host will
accept messages temporarily, and pass it along when a
lower-numbered host becomes available.
Alternate MX sites should have separate Internet connections in order to be most useful. Your ISP can provide this service.
When configuring a MTA for a network, any mail sent to hosts in its domain should be diverted to the MTA so that users can receive their mail on the master mail server.
To make life easiest, a user account with the same username should exist on both the MTA and the system with the MUA. Use adduser(8) to create the user accounts.
The MTA must be the designated mail exchanger for each workstation on the network. This is done in theDNS configuration with an MX record:
This will redirect mail for the workstation to the MTA no matter where the A record points. The mail is sent to the MX host.
This must be configured on a DNS server. If the network does not run its own DNS server, talk to the ISP or DNS provider.
The following is an example of virtual email hosting.
Consider a customer with the domain customer1.org
, where all the mail
for customer1.org
should be
sent to mail.myhost.com
. The
DNS entry should look like this:
An A
> record is
not needed for customer1.org
in order to only
handle email for that domain. However, running
ping
against customer1.org
will not work
unless an A
record exists for it.
Tell the MTA which domains and/or hostnames it should accept mail for. Either of the following will work for Sendmail:
Add the hosts to
/etc/mail/local-host-names
when
using the FEATURE(use_cw_file)
.
For versions of
Sendmail earlier than 8.10,
edit /etc/sendmail.cw
instead.
Add a Cwyour.host.com
line to
/etc/sendmail.cf
. For
Sendmail 8.10 or higher, add
that line to
/etc/mail/sendmail.cf
.
All FreeBSD documents are available for download at http://ftp.FreeBSD.org/pub/FreeBSD/doc/
Questions that are not answered by the
documentation may be
sent to <freebsd-questions@FreeBSD.org>.
Send questions about this document to <freebsd-doc@FreeBSD.org>.