feat: Add admin commands for managing users' email addresses

src/core/config/mod.rs

@@ -2461,6 +2461,9 @@ pub struct SmtpConfig {
 	///
 	/// For most modern mail servers, format the URI like this:
 	/// 	`smtps://username:password@hostname:port`
+	/// Note that you will need to URL-encode the username and password. If your
+	/// username _is_ your email address, you will need to replace the `@` with
+	/// `%40`.
 	///
 	/// For a guide on the accepted URI syntax, consult Lettre's documentation:
 	/// https://docs.rs/lettre/latest/lettre/transport/smtp/struct.AsyncSmtpTransport.html#method.from_url