Unfortunately IMAP is basically entire ephemeral. The message IDs are mostly permanent, but the rfc says they can change so clients have to test them as per co

Unfortunately IMAP is basically entire ephemeral. The message IDs are mostly permanent, but the rfc says they can change so clients have to test them as per connection. This means every time you check your mail with an IMAP client it's syncing some of the headers for every message.