Search Function Missing Emails

If the contact is in your contacts, then hovering over the name should show Details.

If it is not in your contacts, then it should show Add to contacts.

Unfortunately you cannot automatically add reply addresses to your contacts, but you can add them manually from the Recipient History in Menu > Tools > Settings > Mail > Compose.

You can select all the entries at one time, and choose Add to contacts.

I have same Problem with search, it is not reliable to find email you are looking for. It is basic function, I turned on download for offline work