Privacy Policy

Last updated: May 16, 2026

This policy explains what happens to your email address and related information when you subscribe to our mailing list (the “Mailing List”). The Mailing List is used to send subscribers email about happiness research and related work led by Matt Killingsworth.

Scope

This policy applies to the Mailing List only. It does not cover:

• The Track Your Happiness project, which has its own privacy policy
• Any other website, service, or activity, including offline communications

If you signed up via Track Your Happiness, your use of TYH continues to be governed by the TYH privacy policy and your study consent (if applicable), not this policy. Only your email address is transferred to the Mailing List, with no other TYH information attached.

Who we are

The Mailing List is operated by Matt Killingsworth (the “data controller” under GDPR), based in the United States. Email is sent from the domain updates.mattkillingsworth.com. Privacy questions can be sent to privacy@mattkillingsworth.com.

What we collect

When you sign up we collect:

• Your email address
• Signup metadata, such as the source page and approximate country inferred from your IP address
• Engagement data with the messages we send, such as opens and clicks

How we use it

Your email address is used to send you Mailing List emails about this work, as well as operational messages (for example, confirming a signup or notifying you of material changes to this policy).

We may use signup metadata and engagement data to decide which messages to send you (for example, to share an announcement with subscribers who haven’t already responded, or to vary content by audience).

We do not sell, rent, or share your information with third parties for their marketing purposes.

Legal basis (GDPR)

We process your data on the basis of your consent, given when you sign up. You can withdraw consent at any time by clicking “unsubscribe” in any email or by writing to privacy@mattkillingsworth.com.

Service providers

We use third-party service providers to operate the Mailing List, including for email delivery, signup forms, hosting, and analytics. All such providers act under appropriate data-processing terms. We are happy to identify our current providers on request.

International transfers from the EU/UK to the United States or elsewhere rely on Standard Contractual Clauses (SCCs) and the providers’ own compliance programs.

Other disclosures

We may disclose your information:

• To comply with applicable law, legal process, or government requests
• To protect the rights, property, or safety of the Mailing List operator, subscribers, or others
• In connection with a sale, merger, transfer, or reorganization of the Mailing List or related activities, in which case the recipient will be bound by terms at least as protective as this policy
• With your consent

We may also share aggregated or de-identified information (for example, total subscriber counts or aggregate click rates) that does not identify any individual.

Retention

We keep your email until you unsubscribe or request deletion. After unsubscribe, we may retain minimal information to honor your preferences (for example, to prevent re-adding you).

Your rights

Regardless of where you live, you can:

• Unsubscribe at any time
• Request a copy of the data we hold about you
• Request correction or deletion
• Ask questions about how your data is handled

Under GDPR (EU/UK), you additionally have the right to data portability, to restrict processing, to withdraw consent, and to lodge a complaint with your national data protection authority.

Under the CCPA/CPRA (California), you additionally have the right to know what we collect, to delete, to correct, to opt out of sale or sharing (we do neither), and to non-discrimination for exercising these rights.

To exercise any right, email privacy@mattkillingsworth.com.

Children

The Mailing List is not intended for anyone under 16. We do not knowingly collect information from anyone under 16.

Changes

If we change this policy, we will post the updated version here with a new “last updated” date. Material changes affecting how we handle your data will be announced by email.

Contact

Privacy questions: privacy@mattkillingsworth.com.