Bind : MX record for send/receive mails

[Joseph Begumisa]

> I would like to know on how the MX record functioned in BIND for
> sending or receiving emails. Currently, I have a domain (eg:
> domain1.com) with MX records that used other domain's SMTP server for
> sending & receiving emails. (eg: smtp.domain2.com).
>
> $ORIGIN com.
> domain1    IN      SOA     ns1.domain1.com. root.ns1.domain1.com.
>                           (2001082401 3600 300 604800 43200)
>            IN      NS      ns1.domain1.com.
>            IN      NS      ns2.domain1.com.
>            IN      MX      10 smtp.domain2.com.
>
> Questions:
>
> 1) Can it works as the smtp server is in different domain ?
> In other words, can it rely on other smtp server which is not in the
> same domain to deliver or retrieve the emails?

Sure it can.  The MX record would only direct mail for that domain where
to go.  After that it is only a matter of telling the MTA on that
smtp.domain2.com how to treat that mail.

> 2) Do I have to run the smtp services on the local mail server as the
> MX record is already pointing to other smtp server in the different
> domain as the Mail Exchange ?

If you are not going to be using it for sending  mail you don't need to.
You can always set your POP3 & SMTP servers to smtp.domain2.com

> 3) Can a user1 at domain1.com send or receive emails to user2 at domain3.com
> if the MX record for domain1.com is using smtp.domain2.com ? (Notes:
> All domains is located in different networks/geographical)

Sending mail to user2 at domain3.com involves looking up the MX records of
domain3.com so you can send that person mail.  Receiving mail still
involves the lookup of MX records and therefore according to the records
in the primary NS for your domain, the mail will go to smtp.domain2.com.
You can then use suitable methods to bring down your mail to your local
machine.

Joseph.