> Currently, our system is using a 64K ISDN dial-up. As you all know, ISDN
> dail-up is not UP all the time and it only active when there is people
> surfing or activiti in the internal network. We also have a fix ip address.
> We are using linux firewall and have a mail server in our local network
> (behind the firewall). Our parent company have a 64K lease line. So since
> we can't host our internet mail server in our organisation( we are using
> ISDN dial-up), so we make use of our parent company lease line to host our
> mail server. We register our domain name and whatever mail for this domain,
> it will send to the mail server that we set up and located in our parent
> company. So when a user want to read a mail, they need to connect to the
> mail server in the parent company to retrieve mail. Sometime it is very
> uncovenience and sometime the downloading mail from this mail server to the
> user workstation is very very slow. So what you guy will suggest to solve
> this problem?
I can think of three main approaches.
1. Configure the online server as a backup MX for the domain, and your
local server as the primary MX, i.e.
IN MX 0 mail.sister.com.my
IN MX 5 mail.parent.com.my
Programs which send mail to user@sister.com.my will try to send it to
your local server, which will fail, so they will then send it to the
online server. This will attempt to forward it to your local server at
regular intervals.
You may wish to use IP firewalling to prevent anything other than the
online server from connecting to the local server's SMTP port. This
will ensure that mail always goes via the online server.
Alternatively, if the online server uses a different DNS server to the
domain's published server, you can just omit the primary MX from the
public version of the DNS.
2. Configure the online server to use sendmail's mailertable feature
to forward mail for user@sister.com.my to your local server. This way,
the online server is the only MX for the domain.
3. Configure the online server to deliver mail for user@sister.com.my
to a multidrop mailbox. Your local server would then retrieve the
contents of this mailbox via POP3 at regular intervals, and distribute
the mail to the appropriate users (e.g. using fetchmail).
The online server would need to be configured to add an X-Envelope-To:
header containing the envelope recipient address, so that you can
distribute the mail to the correct users.
The last approach is probably the most complex, but it has the
advantage that mail is considered `delivered' once it reaches the
online server. This prevents senders from receiving `could not send
messsage for past 4 hours' warning messages.
-- Glynn Clements <glynn@sensei.co.uk> - To unsubscribe from this list: send the line "unsubscribe linux-net" in the body of a message to majordomo@vger.rutgers.edu