> Also the minus (-) sign character is - per mail RFC - a standard and default character that may not be used in some special form but recognized as a normal character. The + sign is specified exactly for the use that protonmail and others like gmail uses them: add an alias-like mail address.
This is specifically why we need this, especially for custom domains. If the RFC alone allows you to deduce the address is an alias, and the root address behind it, then there is no privacy whatsoever. Even within the RFC it is up to ProtonMail to decide how they route the mail in their different mailboxes, and these aliases need to appear to the outside as actually different mailboxes.
> Also the minus (-) sign character is - per mail RFC - a standard and default character that may not be used in some special form but recognized as a normal character. The + sign is specified exactly for the use that protonmail and others like gmail uses them: add an alias-like mail address.
This is specifically why we need this, especially for custom domains. If the RFC alone allows you to deduce the address is an alias, and the root address behind it, then there is no privacy whatsoever. Even within the RFC it is up to ProtonMail to decide how they route the mail in their different mailboxes, and these aliases need to appear to the outside as actually different mailboxes.