[geary/mjog/message-id-critical-saving-draft] Geary.RFC822.Message: Fix critical when saving draft

[Michael Gratton <mjog src gnome org>]

commit 5aef5125765f13d9a983723d1f523ff74544d02a
Author: Michael Gratton <mike vee net>
Date:   Thu Mar 26 08:24:34 2020 +1100

    Geary.RFC822.Message: Fix critical when saving draft
    
    Message-Id will be null when saving a draft, don't assume it's not.

 src/engine/rfc822/rfc822-message.vala | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)
---
diff --git a/src/engine/rfc822/rfc822-message.vala b/src/engine/rfc822/rfc822-message.vala
index 1ee7b698..b7df6725 100644
--- a/src/engine/rfc822/rfc822-message.vala
+++ b/src/engine/rfc822/rfc822-message.vala
@@ -139,11 +139,6 @@ public class Geary.RFC822.Message : BaseObject, EmailHeaderSet {
         this.date = email.date;
         this.message.set_date(this.date.value);
 
-        // Not actually required, but effectively required since
-        // otherwise mail servers will treat email as spam
-        this.message_id = new MessageID(message_id);
-        this.message.set_message_id(message_id);
-
         // Optional headers
 
         if (email.to != null) {
@@ -175,6 +170,11 @@ public class Geary.RFC822.Message : BaseObject, EmailHeaderSet {
                 this.message.add_mailbox(REPLY_TO, mailbox.name, mailbox.address);
         }
 
+        if (message_id != null) {
+            this.message_id = new MessageID(message_id);
+            this.message.set_message_id(message_id);
+        }
+
         if (email.in_reply_to != null) {
             this.in_reply_to = email.in_reply_to;
             // We could use `this.message.add_mailbox()` in a similar way like