Some quick notes for myself about using doveadm and managing mailboxes. It should be no surprise, that if you are an admin with a server, you can read any email/files on that server.
List users
doveadm user '*'
List mailboxes for user
doveadmm mailbox list -u <user>
Show messages in trash for user older than 30 days
doveadm search -u <user> mailbox Trash NOT SINCE 30days
Delete messages in trash for all users older than 30 days
doveadm expunge -A mailbox Trash NOT SINCE 30days
Delete messages from users mailbox older than 6 months and not flagged
doveadm expunge -u <user> mailbox <mailbox> NOT SINCE 26weeks NOT FLAGGED
Output and users email
doveadm fetch -u <user> "text" MAILBOX <mailbox> UID <email_uid>
Fix index on a mailbox
doveadm index -u <user> <mailbox>
Sync users mailboxes with backup server
doveadm -v sync -u <user> -d