Fix #4982: Allow to send unverified securejoin messages to protected chats

src/mimefactory.rs

@@ -316,7 +316,15 @@ impl<'a> MimeFactory<'a> {
         match &self.loaded {
             Loaded::Message { chat } => {
                 if chat.is_protected() {
-                    PeerstateVerifiedStatus::BidirectVerified
+                    if self.msg.get_info_type() == SystemMessage::SecurejoinMessage {
+                        // Securejoin messages are supposed to verify a key.
+                        // In order to do this, it is necessary that they can be sent
+                        // to a key that is not yet verified.
+                        // This has to work independently of whether the chat is protected right now.
+                        PeerstateVerifiedStatus::Unverified
+                    } else {
+                        PeerstateVerifiedStatus::BidirectVerified
+                    }
                 } else {
                     PeerstateVerifiedStatus::Unverified
                 }