Privacy Policy — Homo Optimus

Last updated: [01-09-2026]

Who is responsible

Homo Optimus is a personal newsletter published by Yannick Delvaux, based in Belgium. For the purposes of the EU General Data Protection Regulation (GDPR), I am the data controller for the personal data described below.

You can reach me at blog@homo-optimus.com

Substack’s role

This newsletter is published on Substack, Inc., a company based in the United States. Substack operates the platform, stores subscriber records, and sends the emails. Substack processes personal data under its own privacy policy, which you can read at https://substack.com/privacy, and provides contractual safeguards for transfers of personal data out of the EU.

This policy covers what I do with your data. It does not replace Substack’s policy — both apply.

What data I hold, and why

Your email address. Collected when you subscribe. Used solely to send you the newsletter. The legal basis is your consent, given when you subscribed. You can withdraw it at any time using the unsubscribe link at the bottom of every email.

Your name or display name, if you provided one to Substack.

Anything you send me. If you reply to an email, comment on a post, or contact me directly, I keep that message. The legal basis is legitimate interest — being able to hold a conversation with someone who wrote to me.

Aggregate statistics. Substack shows me open rates, subscriber counts and similar figures. I look at these in aggregate to understand whether people are reading. I do not use them to profile individual subscribers.

What I do not do

I do not add any analytics, tracking pixels, or third-party scripts of my own. The Substack platform sets its own cookies, which are governed by Substack’s policy and the consent notice you see on the site. I add nothing on top of it.

I do not sell, rent, or share your data with anyone.

I do not use your data for advertising.

I do not use subscriber replies to train anything, publish anything, or build any list beyond the newsletter itself.

Health information

This newsletter documents self-experiments involving my own health and physiological data. Two things follow from that.

My data is mine. The measurements, results and observations published here are my own, collected voluntarily and published deliberately. No subscriber data is involved in any experiment.

Yours is yours. Readers sometimes reply with details about their own health. Information of that kind is treated as sensitive under the GDPR, and I do not seek it. If you send it to me anyway:

It stays in my email inbox. I do not enter it into any database, spreadsheet, or analysis.

I will never publish it, quote it, or refer to it publicly without asking you first and getting a clear yes.

You can ask me to delete it at any time, and I will.

Please do not send me medical records, test results, or detailed health histories. If you want to discuss something specific about your own health, speak to a doctor rather than to me.

How long I keep things

Your subscription record is kept for as long as you remain subscribed. If you unsubscribe, Substack retains the record according to its own retention practices; you can ask Substack to delete your account data directly.

Correspondence is kept in my inbox indefinitely unless you ask me to delete it.

Your rights

Under the GDPR you have the right to:

• ask what personal data I hold about you

• have inaccurate data corrected

• have your data deleted

• object to or restrict how I use it

• receive a copy of it in a portable format

• withdraw consent at any time

To exercise any of these, email me at blog@homo-optimus.com. I will respond within one month.

Some of these rights are best exercised directly with Substack, since Substack holds the underlying records. I will help where I can either way.

If you are unhappy with how I have handled your data, you can complain to the Belgian Data Protection Authority (Gegevensbeschermingsautoriteit / Autorité de protection des données), or to the supervisory authority in your own country if you live elsewhere in the EU.

Children

This newsletter is written for adults and is not directed at children. I do not knowingly collect data from anyone under 16.

Changes

If this policy changes in any meaningful way, I will update the date at the top and mention it in a post.