How can I set up my mx records to a remote server

Question

Normally when I host a client on one server and use another server for email, it's quite simple to set up mx records like this:

Priority  Host
5         smtp.somehost.com
5         inbound.somehost.com

That kind of setup is straightforward enough. However, I currently have a client who's mail is on a netfirms.com server and the information I got from them when I asked about mx settings was a very terse:

Mx priority 30
Host @
point to mx.netfirms.com

Currently an nslookup shows:

mail exchanger = 30 mx.mycustomersdomain.com.

...and telnet to mx.mycustomerdomain.com on port 25 shows:

220 bosimpinc12 bizsmtp ESMTP server ready

I'm finding it difficult to translate that into a standard mx record and I don't want to experiment too much with a live email server and cause too much interruption to my client. Since I only have two settings per mx record in my admin panel (priority and host), should this be simply set up as:

Priority  Host
30        mx.netfirms.com

By simply including this mx record, can I take it that the netfirms server will know what to do with smtp/inbound emails? If so, what significance does the '@' have here? should that be a separate record?

many thanks, Mike.

Answer 1

From BIND documentation:

When used in the label (or name) field, the asperand or at-sign (@) symbol represents the current origin.

So, this (when in example.com zone)

@ MX 30 mx.netfirms.com

is the same as this

example.com MX 30 mx.netfirms.com

which essentially means "direct all mails for @example.com to SMTP server on address mx.netfirms.com. The example.com part is usually implied, especially if you have some sort of web UI to edit your DNS zone, so yes, your assumption is correct.

More important, the answer to your second question is no, the fact that you entered netfirm SMTP server as your MX does not mean netfirms server will know what to do with smtp/inbound emails for that domain (unless it is [unrelated to your MX settings] previously explicitly set up to do so)