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An Explanation of Mail-Exchanger or MX Records

MX records are a specific type of DNS record, stored on 1000s of DNS servers around the Internet, which form the mechanism for getting emails delivered to the right place.

When a mail-server has an email to deliver to it asks its nearest DNS server for the name of the computer responsible for accepting email for addresses at
This name is contained in the MX record for the domain and, once the sending mail-server knows what this is, it will connect to this mail-server and attempt to deliver the email.

There's a bit more to the MX record system:-
You can have multiple MX records for an email domain, and each record can have a different priority.
The MX records for addresses might be:- - priority 5 - priority 10
The lower the number, the higher the priority.

A sending mail-server will first try to send an email destined for a address to the computer called
However, if this computer fails to respond within a certain time period, it will then try to send the email to the computer called instead.
If neither respond it will wait a short period and then try the first one again.

This is a great automatic backup system that ensures that email will continue to be delivered if the main mail-server computer, in this case, fails.

What are the MX Records for Your Company's Email Domain?

Here's how to find out:-
Open a Command Prompt window on your PC by clicking:-
Start - Run
Type CMD and then click OK

Then type the following commands (each one followed by pressing Enter):-
set type=mx
(substitute a real domain for this)

And you should see your MX records.

Press Ctrl+C to break out of the NSLookup command, then type exit to close the window.

How Do the Big Boys do it?

The following Command Prompt window shows the MX records for:-
Hotmail has 4 x MX records of equal priority but there are 4 separate mail-servers for each MX record. This is for load balancing and redundancy.

Command Prompt window showing the MX records for, and

Here are Arrowmail's MX Records

Command Prompt window showing the MX records for

Why not check yours now?
If you have trouble finding your MX records then email us at and we'll email you back a printout of your MX records.

How To make Changes to Your MX Records

You need to make all changes to your DNS records using the control panel webpage provided by the company your domain is registered with.
If you can't remember who this is, go to this page:-
and enter your domain name in the "Is my domain name available?" box.
The next page will say that it's not available and your domain should show up in the Unavailable Domain Names table.
Click on the Whois Information link for your domain and the Registrar entry is the company your domain is registered with and then go to their website.
You may need to contact them to find your username and password in order to make changes.

Many domain registration companies now have a DNS control panel, accessible from a
web-page, where you can change the values yourself (take care when changing your own DNS records!).
One common trap is that DNS control panels often require you to add a final full-stop to the end of a new DNS record for it to be valid, such as:-

Once you make changes to your MX records, nothing will happen for a few hours and then emails will gradually start to arrive at the computer named in the changed MX record, but it may be up to 48 hours before the majority of mail servers on the Internet are using your updated MX record and perhaps up to a week before a few stragglers stop using the old records.
So if you need to add a standby mail-server record for your email system, the time to do it is before you actually need it.

If you need to modify your MX records so that our servers are the main or standby
mail-servers for your email domain and don't fancy doing this yourself, let us know the logon details for your domain registrar's control panel and we'll be happy to do it for you.

Moving your Domain to a new Domain Registrar

If you ever need to change the company your domain is registered with, the responsible DNS servers are also likely to be switched to the new company.
When this happens all your existing DNS records will be lost so it's a good idea if you can setup the same records, using the new company's DNS control panel, before the switch occurs.

You don't have to use the DNS servers provided by your domain registrar.
Most domain registrar control panels also allow to specify the DNS servers that are responsible for your domain.
We provide DNS Hosting and management for £1.85/month if you are struggling with your current DNS provider - for details go to

If you were using a 3rd party DNS provider, your existing DNS records would remain intact after switching registrar companies and then you would only have to make sure that the new registrar had the correct DNS servers specified.

If you aren't planning to move domain registrars and you don't have any unusual DNS requirements, it's usually fine to stick with the DNS servers provided by domain registrar.

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