Keep order of contacts in parsed To: and similar headers

Author: link2xt

Diff for: src/receive_imf.rs

@@ -3026,7 +3026,8 @@ async fn add_or_lookup_contacts_by_address_list(
     address_list: &[SingleInfo],
     origin: Origin,
 ) -> Result<Vec<ContactId>> {
-    let mut contact_ids = HashSet::new();
+    let mut contact_ids = Vec::new();
+    let mut contact_ids_set = HashSet::new();
     for info in address_list {
         let addr = &info.addr;
         if !may_be_valid_addr(addr) {
@@ -3037,13 +3038,16 @@ async fn add_or_lookup_contacts_by_address_list(
             let (contact_id, _) =
                 Contact::add_or_lookup(context, display_name.unwrap_or_default(), &addr, origin)
                     .await?;
-            contact_ids.insert(contact_id);
+            if !contact_ids_set.contains(&contact_id) {
+                contact_ids.push(contact_id);
+                contact_ids_set.insert(contact_id);
+            }
         } else {
             warn!(context, "Contact with address {:?} cannot exist.", addr);
         }
     }
 
-    Ok(contact_ids.into_iter().collect::<Vec<ContactId>>())
+    Ok(contact_ids)
 }
 
 #[cfg(test)]