SPF Setup for ProtonMail Custom Domains

December 22, 2025 • InboxGreenEmail Team

🚨 DKIM issues can silently kill replies.

If opens dropped, replies disappeared, or bounces increased, treat it as an incident. Run the scan and get a fix path.

No signup required. Works on any domain.

search Run a Free Domain Check notifications_active Monitor my domain

Introduction

Setting up SPF for your custom domain on ProtonMail can be a bit tricky. If you are a SaaS founder, marketer, or someone who manages email sending, you know how crucial it is to ensure your emails land in the inbox and not the spam folder. A misconfigured SPF record can lead to bounced emails, warnings in Gmail, or worse, getting flagged as spam. This is not just a technical issue; it can severely impact your domain reputation and overall email deliverability.

When you start seeing issues like emails not being delivered or landing in spam, it becomes urgent to address your SPF setup. In this article, we will walk through the practical steps to set up SPF for your ProtonMail custom domain, ensuring your emails are authenticated properly and have a better chance of reaching your recipients.

At a glance

  • This problem affects anyone using custom domains with ProtonMail.
  • This article will guide you through the SPF setup process.
  • By following these steps, you will improve your email deliverability and domain reputation.

When this problem shows up in real life

Let’s look at some real world scenarios where SPF issues might surface:

  • Gmail Warnings: You send an email to a client, but they reply saying your email landed in the spam folder. Checking the headers, you see a warning: "SPF fail". This indicates that Gmail could not verify your sending domain.
  • Bounced Emails: You receive a notification that an email bounced back. The error message states "550 5.7.1 Sender address rejected: Domain not found". This often happens when the SPF record is missing or incorrectly configured.
  • Support Tickets: A customer opens a support ticket complaining they are not receiving your emails. Upon investigation, you find that your domain is not properly authenticated, leading to deliverability issues.

Step by step: SPF setup for ProtonMail custom domains

  1. Log in to your ProtonMail account.

    Navigate to the settings by clicking on the gear icon in the top right corner.

  2. Access the domain settings.

    In the settings menu, find the "Domains" section. Here, you can add your custom domain if you haven't done so already.

  3. Create your SPF record.

    ProtonMail requires you to add an SPF record to your DNS settings. The SPF record will look something like this:

    v=spf1 include:_spf.protonmail.ch ~all

    This record allows ProtonMail to send emails on behalf of your domain. Make sure to replace the existing SPF record if you have one.

  4. Update your DNS settings.

    Log in to your DNS provider's dashboard (like GoDaddy or Cloudflare) and find the DNS management section. Add a new TXT record with the SPF information:

    Type: TXT
Host: @
Value: v=spf1 include:_spf.protonmail.ch ~all
TTL: 3600
  5. Verify your SPF record.

    After updating your DNS, it may take some time to propagate. You can check if your SPF record is set up correctly using the InboxGreen checker.

Common mistakes

  • Missing SPF record:

    Symptom: Emails are bouncing with a "domain not found" error.

    Cause: There is no SPF record configured for your domain.

    Fix: Follow the steps above to create and publish your SPF record.

  • Incorrect SPF syntax:

    Symptom: You receive SPF fail warnings in email headers.

    Cause: The SPF record has syntax errors.

    Fix: Use the SPF generator to create a valid record.

  • Multiple SPF records:

    Symptom: Emails are not being delivered, and you see "multiple SPF records" errors.

    Cause: You have more than one SPF record for your domain.

    Fix: Consolidate your SPF records into a single record.

  • Using "all" incorrectly:

    Symptom: Emails are being flagged as spam.

    Cause: Using "-all" instead of "~all" can cause strict rejections.

    Fix: Change "-all" to "~all" to allow soft fail for unauthorized senders.

Troubleshooting when it still fails

If your SPF record appears correct but you are still facing issues, consider the following:

  • Authentication-Results header:

    Symptom: Emails are still landing in spam.

    Likely cause: The SPF check is failing.

    What to try next: Check the Authentication-Results header in the email to see the SPF status.

  • Propagation delays:

    Symptom: You just updated your DNS but nothing seems to change.

    Likely cause: DNS changes can take time to propagate.

    What to try next: Wait for up to 48 hours and check again.

  • Check for blacklisting:

    Symptom: Deliverability issues persist.

    Likely cause: Your domain might be blacklisted.

    What to try next: Use the Blacklist Checker to see if your domain is listed.

Related checks you should run

  • Ensure SPF, DKIM, and DMARC records are aligned.
  • Check DNS TTL settings and propagation delays.
  • Monitor your domain reputation and look for bounces or spam reports.
  • Evaluate your email list quality and engagement patterns.

FAQ

Why is SPF still failing on ProtonMail after I added the record?

If SPF is still failing, it could be due to DNS propagation delays or incorrect syntax in your SPF record. Double-check your record using the InboxGreen checker to ensure it is valid.

How long do DNS changes take to apply on ProtonMail?

DNS changes can take anywhere from a few minutes to 48 hours to propagate fully. If you have just made changes, be patient and check back later.

Can I use more than one SPF include with this setup?

Yes, you can include multiple SPF records. Just make sure to combine them into a single SPF record using the "include" mechanism. For example: 

v=spf1 include:_spf.protonmail.ch include:anotherdomain.com ~all

What should I do if my emails are still going to spam?

Check your SPF, DKIM, and DMARC records for alignment. Also, review your email content and engagement patterns, as these can affect deliverability.

Is there a way to test my SPF record after setting it up?

Yes, you can use various tools, including the InboxGreen checker, to validate your SPF record and ensure it is functioning correctly.

What to do next

Now that you have set up your SPF record for ProtonMail, it is crucial to monitor its effectiveness. Use the InboxGreen checker to verify your setup and ensure your emails are being delivered as intended. Regularly check your domain's reputation and make adjustments as necessary. If you run into any issues, refer back to this guide or reach out for help. Your email deliverability is vital for your business, so stay proactive!

Free Deliverability Scan

Check SPF, DKIM, DMARC and List-Unsubscribe for your domain in seconds.