DNS MX records and SMTP mail

[compserv]

I have a couple of domains set up on the shared Windows hosting. I shall be running my own mail server (Exchange 2007) in my office, and want to have the mail for one of the domains routed directly to my server.

At the moment the DNS records show an A record for mydomain.co.uk with a value of the web hosting IP Address. I also have an MX(10) record for mydomain.co.uk with a value of mail.mydomain.co.uk, and an A record for mail.mydomain.co.uk with a value of the webhosting IP address.

First, am I correct that all I need to do is to change that last A record to my broadband IP address to get the mail delivered to my server. (I already have mail for the domain provided by my ISP sent to another server in the office)

Second, do eUKHost provide any backup SMTP server (e.g. set up on an MX(20) record) in case my server or line goes down. (I won't be using any POP3 mail on the domain if that matters). If not, what happens to email sent to mydomain.co.uk when there is no server on the end.

Thanks for any help/suggestions.

Roger

[Rock]

Hello Roger,

We don't provide a backup/fail-over SMTP server at the moment, but we'd think of providing such a feature/service shortly..

According to RFC2821, the lowest-numbered records are the most preferred, the lower the priority, the higher the preference to that mail server. Hence you can setup a new MX record with the priority of 0 (zero) & point that to your mail server (Exchange 2007).

The final DNS zone records would look like:

mydomain.co.uk. IN A xxx.xxx.xxx.xxx ; This is the A record of the domain, which doesn't need to be changed.

mydomain.co.uk. IN MX 0 exch.mydomain.co.uk. ; Your local Exchange server's MX record with lowest priority.
mydomain.co.uk. IN MX 10 mail.mydomain.co.uk. ; Our shared server's MX record with the next priority.
mydomain.co.uk. IN MX 20 exch2.mydomain.co.uk. ; Any other exchange mail server's MX record with next higher priority.

mail. IN A xxx.xxx.xxx.xxx ; Our shared server's IP.
exch. IN A yyy.yyy.yyy.yyy ; Your local Exchange mail server's IP.
exch2. IN A zzz.zzz.zzz.zzz ; Any other exchange mail server's IP.

Here email would flow in the direction from the lowest priority to the higher ones [only in terms of their failure].

Mail servers located globally, would query the DNS servers & will by default use the lowest priority records, here exch.mydomain.co.uk would take the lead & do all the mail transactions, while the other 2 would stay calm..

But when exch.mydomain.co.uk [your local mail server] fails, is unreachable for any reasons, the next higher priority mail server [mail.mydomain.co.uk] would kick in, here being our shared server's mail server.

If both of these above mail servers [your local & our shared] are unreachable or down & you've configured a 3rd MX, in this case [exch2.mydomain.co.uk], this mail server would then take charge of the mail transactions.

More info on MX records can be found here : MX record - Wikipedia, the free encyclopedia

Please let us know if you have any further questions

[compserv]

Many thanks for the explanations Rock.

Have you any idea if you do decide to run a backup SMTP server, what sort of timescale that would be?

Roger

[eUK-Gabriel]

We do not have SMTP server to backup master SMTP for our shared servers and can not give exact ETA at the moment but we'd update you once its implemented.
Plesk makes it a bit difficult to to handle more than one mail server. We are planning to switch over to another Control Panel on our shared servers which is capable to handle more than one SMTP server[master as well as slave]