Sender Domains

For maximum email delivery rates and better branding (whitelabelling) it is important to set up a DKIM record and SPF record. This can be done from the Settings > Sender Domains page. You can also specify a subdomain, which will be used in the URLs of any unsubscribe links and for open and click tracking purposes.

DKIM (DomainKeys Identified Mail) is a technique for digitally signing an email, so that a particular domain name can claim responsibility for that email. An SPF record lets the world know which SMTP servers and IP addresses are allowed to send emails from your domain name.

If you don't set up a sender domain, SMTP2GO signs all emails with our own DKIM signature. This works in most situations, however Gmail recipients will see that emails are being delivered "via" or "via". In addition, better email delivery to Hotmail/Yahoo/Gmail/AOL can be achieved by using a DKIM signature at your own domain, and if you need to set up a DMARC record (which is useful to prevent spammers sending phishing emails from your domain name) then DKIM signature at your own domain is essential.

To set up a Sender Domain, follow the steps below:

Step One:

From the left-hand menu, make your way to the 'Settings > Sender Domains' page in your SMTP2GO control panel.

Enter your domain name in the textbox and click 'Add Domain'. For example, if you send your emails from then you would enter

Step Two - Login to your DNS provider:

Login to the DNS administration of your domain name with your DNS provider. If you are unsure where your DNS is hosted, check the top of the page in Sender Domains where you'll see Your DNS provider is...

Step Three - SPF record setup:

Once you are logged into your DNS administration from step two, you're ready to create your SPF record. You do this by creating a DNS record of the type TXT for your domain name by entering the hostname specified and the value specified in the 'Enter this value' field. If you already have an SPF record then you must change that existing SPF record. Do not add a second SPF record for the same domain name.

We have setup guides for popular DNS providers, which can make this easier. More technical information can be found in our guide about creating an SPF record.


Step Four - DKIM record setup:

To create a DKIM record for your domain name, you need to create another DNS record of type CNAME. Enter the hostname specified and the value specified in the 'Enter this value' field.


We have setup guides for popular DNS providers.

If you are using BIND to edit your DNS, then you would create a single line entry, in this format: CNAME "your dkim key"

Step Five - Tracking domain setup (Optional):

If you plan on placing any unsubscribe links in emails that you send out (unsubscribe links are required if you are sending any type of newsletter email, or the same email to many recipients) then we recommend setting up a CNAME record on a subdomain that you choose. This will provide a much better branded experience to your recipients, and your emails will also be judged by any spam filters on the reputation of your own domain name.

Your subdomain will also be used within any open and click tracking URLs in your emails.

Note: whichever subdomain you choose, recipient mail servers and spam filters look at your root domain for reputational purposes.

How do I know it is working?

As long as your domain is showing as 'Verified' in both the SPF and DKIM columns on your Sender Domains page, it is setup and working correctly.  


I’m seeing an error with my DNS settings when trying to add the DKIM record. What can I do?


Some hosts do not support underscores (_) in DNS records, and adding the DKIM record can cause an error. The underscore is required and you’ll want to contact your host and see if they can manually add the record for you or if they disallow underscores entirely.

Semicolons (;)

Some hosts require that you escape semicolons in records. If you’re getting an error, try replacing ; with \; .

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