said David C. Rankin via tde-users:
| Be very, very wary....
I do not know what you're talking about here.
| Protonmail is not accepted by my server and many others due to it | routing mail though APNIC servers in PRC. Starting several years ago, I | have an engineering company I host that found it could no longer receive | mail from proton mail. A quick investigation showed it could no longer | receive mails due to the protonmail server being blocked at the | firewall. It was banned by fail2ban due to repeated illegal intrusion | attempts from that same IP. (dovecot:auth failures)
The next email I send over ProtonMail that is not accepted by a server will be the first.