I'm happy to use a service that is not Gmail or Outlook. And I like the fact that I can use my custom domain easily. In the end I'm not really using it though,

I'm happy to use a service that is not Gmail or Outlook. And I like the fact that I can use my custom domain easily. In the end I'm not really using it though, simply because none of my contacts uses it. In that case ProtonMail is simply begging the question when it comes to privacy and security: You can set an expiry for emails to non-Protonmail recipients, meaning they just receive a link to the contents of the email. Obviously you must also password protect it (otherwise gmail / outlook will just follow the link). Now the point is: how do you safely communicate the password? Either you know how to safely communicate a password; in that case why not send the message without ProtonMail? Or you do not know how to safely communicate a password; what security does ProtonMail offer then?