Email Authentication: SPF and DKIM
Note 1: users sending with MailPoet's Sending Service don't need to set up SPF or DKIM.
Note 2: support for DKIM in MailPoet version 3 is only available for customers of our sending service.
Email authentication is just a fancy word for stuff that helps you avoid ending up in spam folder. By implementing some of these technologies, you can improve your open rate, increase engagement with your readers, and improve your sender reputation. A win for everyone!
In simple terms, both SPF and DKIM work by verifying that a FROM address used on an email is authorized by that website's domain. In other words, they make sure that you aren't pretending to be someone else.
SPF is used by your subscribers' email servers (Gmail, Hotmail, Outlook, self-hosted email, etc.) to verify if the FROM email address you used on your newsletter is authorized by your website.
This is why you can't send a newsletter from a domain that you don't own. This includes free mail services like Gmail and Yahoo Mail. When your subscribers' email servers receive a newsletter from @gmail.com, they will check if you are authorized to use a Gmail email address on a newsletter sent from your website. Since Gmail's servers don't have SPF records for your domain, this means your newsletter was not authorized. As a result, it will end up in the spam folder.
If you want to use a third-party service to send your MailPoet newsletters (like SendGrid or ElasticEmail), you'll need to add their SPF or DKIM records on your website's DNS.
Read these guides from Mail Tester to help you set up an SPF record in your host's DNS records.
DKIM is another TXT record added to your host's DNS records. Your MailPoet install will cryptographically sign your newsletters with a key generated specifically for your domain. When your subscribers receive your newsletter, their email servers will grab the key on your domain's DNS records. Then, it will use this key to perform a cryptographic authentication to make sure your newsletter was not modified during the sending process.
MailPoet users that send their newsletters using a third-party service, like SendGrid or Elastic Email, already have their messages signed by these services with their own DKIM keys. See SendGrid's document on DKIM and Elastic Email's guide.
If you are sending emails with your own website and want to set up DKIM, please contact your host company support. They will be able to setup your DKIM.
Want to check if your DKIM record is working? Just use this handy tool from MailTester: SPF and DKIM check.
Note: it's impossible to modify the DKIM record on 1and1 hosting, unfortunately.