Burner addresses using ProtonMail sieve filter and catch-all

You can get burner like functionality in ProtonMail by using a custom sieve filter, and catch-all email — here is how.

Our custom sieve filter will:

• Only filter email for the catch-all/burner domain
• Discard emails sent to an blocked aliases
• Move incoming emails to a “Catch-all” folder, and mark them as read — unless the recipient alias is in the allow list

require ["fileinto", "imap4flags", "extlists"];

if address :domain "to" "helloworld.com"
{

  ## Blocked aliases
  if anyof(
      address :localpart "to" "facebook",
      address :localpart "to" "twitter"
      )
  {
    discard;
  }

  ## Accepted recipients
  elsif not anyof(
      address :localpart "to" "reddit",
      address :localpart "to" "me"
      )
  {
    addflag "\\Seen";
    fileinto "Catch-all";
  }

}

Okey, so the filter above does the following:

• Permanently deletes email sent to facebook@helloworld.com and twitter@helloworld.com
• Move all emails NOT sent to reddit@helloworld.com or me@helloworld.com into the folder Catch-all and mark them read

There are plenty of services out here that does this more elegantly, like:

• Forward Email
• Burner Mail
• AnonAddy

But for me the sieve filter solution works good enough, and lets me keep all my emails within ProtonMail.