Why is my Gmail email history not fully imported?
In Missive, make sure you are at least subscribed to the Starter plan. Also, make sure you set Missive to import your entire email account history. If you are still not seeing your history imported, you might be limiting the number of emails available to the IMAP connection, see this option in your Gmail settings under Forwarding and POP/IMAP, under the Folder Size Limit section: