Mail saves message fields and attachments with drafts, so an unsent message remains available to edit after a sending problem. Recipient suggestions search Contacts in the selected team. Team admins can remove unused alias and reject routes, and can remove an empty mailbox. Messages in Trash can be restored or permanently deleted with their attachments.
More complete Mail drafts and cleanup
Mail drafts save attachments as you write, Contacts can help fill recipients, and messages in Trash can be removed permanently.