Privacy notice

Last updated: 5 May 2026

Who runs this site

This site is run personally by Matti T. J. Heino (matti@mattiheino.com). newsletter.mattiheino.com is not affiliated with any institution. If you'd like to contact me about anything here, write to that address.

What I collect

When you sign up to the newsletter, I collect:

• Your email address (required – I cannot send you anything without it).
• Your first name (optional – used in greetings if you give it).
• The topics you ticked at sign-up (so I send only what you asked for).
• If you ticked one of the courses, your free-text answer per course to "what would you like to learn?" (optional). Each course has its own answer field; used to orient what I plan; not shared.

I do not run analytics on this page, log IP addresses, or fingerprint browsers. Cloudflare (the DNS service in front of the site) sees IP addresses for routing and basic security purposes; Cloudflare does not retain those for me and I cannot see them.

Why I have your data

To send you the emails you opted into, and only those. Each topic you tick is a separate consent; you can unsubscribe from any one without affecting the others.

The legal basis under the GDPR (Article 6) is consent – yours, given at the form and confirmed by clicking the link in the confirmation email.

Where your data lives

On a server I rent from Hetzner Online in the EU. The mailing-list software (Listmonk) and its database (PostgreSQL) both run there.

To deliver the emails reliably, the messages pass through MailerSend (operated by MailerLite, headquartered in Lithuania, EU). MailerSend sees the recipient address and the message content for as long as delivery requires.

DNS for the site routes through Cloudflare (an Irish-headquartered company). Cloudflare does not see the sign-up data itself.

I do not share, sell, or trade your data. No third parties beyond MailerSend and Cloudflare touch it.

How long I keep it

Until you unsubscribe or ask me to delete it. There is no automatic deletion timer. If you stop opening emails for a long time, I may quietly drop you from the active list (stale lists hurt deliverability for everyone), but the record itself stays archived unless you ask me to erase it.

Your rights under GDPR

You can:

• Unsubscribe any time using the link at the bottom of every email. Each topic has its own unsubscribe; leaving one does not leave the others.
• Ask for a copy of the data I hold about you (email and any name you submitted).
• Ask for it to be corrected or deleted.
• Ask for it to be ported to another service.
• Object to my using it.
• Complain to a data-protection authority. In Finland that's the Tietosuojavaltuutetun toimisto.

For any of these, write to matti@mattiheino.com with what you'd like. I'll act within 30 days.

Changes to this notice

If I change anything material, I'll update the date at the top of this page and, where the change affects active subscribers, mention it in the next email. The current version is what governs.