For open correspondence, use email:

Details in case you're worried about the privacy our correspondence

My email is located in the cloud of the ProtonMail mail service, on Swiss servers. I receive and send mail only through official clients, which protects against the interception of letters on the way from me and to me.

If you are worried about the privacy of our correspondence, encrypt the message with PGP and send it to the same email. Be sure to share your PGP public key with me, so I can add you to my contacts and encrypt the reply email.

My PGP key: 985FE55E

Keep in mind that with PGP, the body of the email is always encrypted, but the subject of the email is transmitted in plaintext and the fact that there is encrypted correspondence is available to a potential interceptor. If you want to discuss something privately, invite me to coffee in the park.