SPF stands for Sender Policy Framework. It's an email authentication standard that allows a domain to publish a public list of which mail servers are permitted to send emails on its behalf. SPF is the most effective way to prevent spammers from using your domain name. The technique works by sending servers checks with SPF data, which compares sending IP addresses to the ones registered by the sender's domain.
ProtonMail highly recommends that you configure SPF for all your registered domains to make sure your outbound emails are effectively authenticated.
How to Create an SPF Record for ProtonMail?
In order to generate your SPF record on ProtonMail, log in to your ProtonMail account and navigate to Settings → Organization → Custom domains → Actions → Review button → SPF.
Here you will find your SPF record for ProtonMail. Simply copy and paste it into your DNS.
Or, you can also publish your record for ProtonMail without having to log into your ProtonMail account. For that, follow the steps shown below:
Login to your DNS management console
Navigate to Tools & Settings > DNS Template
You need to edit the DNS TXT record related to SPF
An SPF TXT record for ProtonMail will have the following syntax:
yourdomain.com TXT v=spf1 include:_spf.protonmail.ch -all
Publish this record in your DNS records section for your respective domain.
Note: If you don’t have an SPF record previously for your domain, simply publish the above-mentioned record to enable SPF for outgoing emails using ProtonMail. If you do have an existing SPF record in your DNS, you need to modify it to include ProtonMail, as shown below:
Previous SPF record: v=spf1 mx include:spf.domain.com -all
Modified SPF record: v=spf1 mx include:spf.domain.com include:_spf.protonmail.ch -all
DO NOT add multiple SPF records.
Wait for 48-72 hours to allow your DNS to process the changes