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Updated – Using a custom domain with Extravision

July 15, 2015

Using a custom domain for your email marketing has many advantages while still allowing Extravision to handle your incoming messages. Having your own branding in your email domain means that you can maintain your online branding and it helps to reassure the recipient that the email they are receiving is from someone they recognise and trust. All this makes it more likely the recipient will open and read your email and not simply delete it. This document explains how to implement your custom domain and setup the authentication required for deliverability.

The first thing you need to do is choose your custom domain. Generally sub domains of your corporate domain are the best option for branding but you can use any domain. Some examples for the company “mycompany” are:

  • email.mycompany.com
  • news.mycompany.com
  • marketing.mycompany.com
  • mycompany-email.com

It doesn’t really matter which domain you choose so long as it is not already being used and it does reflect your brand in someway. It is important to remember that this domain cannot be used for anything else since all web and email traffic will be directed to Extravision.


With the ever increasing problem of spam it is becoming more and more important that an email can prove that it comes from the domain it claims to be sent from. Email authentication helps with this by letting you add some simple information to your domain name's DNS records that says who is allowed to send email for this domain.

There are two main authentication standards that we support called SPF and DKIM. Some older standards have been depreciated and are no longer used. These are Domainkeys and SenderID.

All the large ISP's such as AOL, Hotmail, Yahoo! and Google are using email authentication to control the amount of spam delivered to their users. It is also a standard module in a number of web and hardware firewalls used by many companies. By setting up authentication on the domain you can bypass certain filters and improve the chance your email will be delivered to the inbox. Some ISP’s such as Yahoo! and Hotmail also mark the email as authenticated in the inbox which gives the recipient greater confidence to open and read your email.

Configuration - Let us do it

All authentication for a domain is control by Domain Name System(DNS) records. Without it there would be no internet. Think of it as an address book for the internet. You give it a machine name i.e. www.extravision.com and it returns with the address of the machine so you can find it on the web.

Your DNS may be hosted internally, by your ISP or by a third party company. If you are unsure then a good place to start is whoever looks after your website. They should be able to point you in the right direction.

The easiest way to enable authentication for a sending domain is to redelegate control of the domain or sub-domain to the Extravision name servers. This enables our engineers to create the necessary DNS records without you needing to do anything. If you wish to re-delegate control of a domain to us for authentication then please email [email protected] with the name of the domain and we will give you the correct nameserver details.

Configuration - Setup DNS yourself

To route all web and email traffic to our servers you need to create two different types of DNS records. An A record and an MX record.

An A (address) record, sometimes called a host record, is a DNS record that is used to point a domain name to the IP address of a server. In order for our application to use your domain in tracked links we need the A record for the domain to point to our server.

The A record should point to

A mail exchanger record (MX record) is a type of resource record in DNS that specifies a mail server responsible for accepting email messages on behalf of the recipient’s domain. In order that we can process all bounces and replies from your campaigns, this record needs point to our mail server.

The MX record should point to mail1.evmailer.com.

*Note – It is important not to miss the dot at the end of the domain name. This tells DNS that this is the end of the record and not to append the domain itself. Without the dot the MX record will be mail1.evmailer.com.mycompany.com and not mail1.evmailer.com as it should be.

DNS changes do not always take affect the moment you make them. It can take up to 48 hours for the DNS to propagate around the world. After a 48 hour period you can check that the records have been created correctly by using one of these sites.


You need to check that what is returned for the MX and A records matches what is in this document.

SPF Record

SPF allows the owner of a domain to use a special format of DNS TXT record to specify which machines are authorised to transmit email for that domain. A TXT record is a DNS record used to hold some text information that is associated with a domain. In this case the SPF record. The SPF record you need to include is below:

v=spf1 include:evmailer.com -all


DKIM is a protocol for validating and authenticating emails. The keys are small pieces of information stored within each email that allow the receiver to verify who the email came from and that the message hasn’t been altered during delivery.

To help with the configuration we use one of our technology partners, Port25 and the configuration tool they have on their website.

1. Visit the Port25 DKIM wizard website here

2. Enter your domain name in the box provided. For example, if your sub-domain is mail.mycompany.com then enter “mail.mycompany.com”

3. The domain key selector is used to specify which key is to be used to sign an outgoing email. This can be anything so the example of key1 is fine.

4. Keep the default key size of 1024 bits

5. Select “Create Keys”

The instructions on the next page tell you which DNS records you need to create for DKIM. There are 2 TXT records that you need to create, the Selector record and the Policy record.

Steps 2 & 3 are for Extravision to implement. Please save a copy of the page and email it to [email protected] We will reply and let you know as soon as your DKIM has been setup and verified.



Posted by Simon Hill
Deliverability, Technology

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