I came across a website that implemented the option to leave a note or comment in a way I had not seen before. It's a rather cool alternative to sending them a mail or submitting a message via a form.

I had to ssh note@website.com*, and when the connection was established, it asked for the note and some optional personal information.

Note: Oh, this is a great idea!
Name (optional): Mészáros Róbert
URL (optional): https://www.implenton.com/

Once I submitted the information, there was a thank you message, and the SSH connection was terminated.

Since it was a developer-oriented website, typing something in the terminal for the reader might be even simpler than all other options.

*I won't share the actual domain here because it was posted on a Gemini capsule. That would be a breach of "confidentiality". It's up to your imagination or for you to implement it.