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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 jsmith@companymail.com it asks its nearest DNS server for the name
of the computer responsible for accepting email for addresses at
companymail.com.
This name is contained in the MX record for the
companymail.com 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
@companymail.com might be:-
mail1.companymail.com - priority 5
mail2.companymail.com - priority 10
The lower the number, the higher the priority.
A sending mail-server will
first try to send an email destined for a companymail.com address to the
computer called mail1.companymail.com.
However, if this computer fails
to respond within a certain time period, it will then try to send the
email to the computer called mail2.companymail.com 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 mail1.company.com, 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):-
nslookup
set type=mx
companymail.com (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:-
btinternet.com
hotmail.com
gmail.com
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.
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Why not check yours now?
If you have trouble finding your MX records then email us at
support@arrowmail.co.uk 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:-
http://www.easyspace.com
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:-
mail1.companymail.com.
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 www.dnsmax.co.uk
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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