# egrep -v '^(#|[ t]*$)' /etc/dovecot/conf.d/99-migration.conf
imapc_host = imap.gmail.com
imapc_features = rfc822.size
imapc_features = $imapc_features fetch-headers
mail_prefetch_count = 20
imapc_port = 993
imapc_ssl = imaps
imapc_ssl_verify = yes
imapc_features = gmail-migration

# sed -n '/^namespace inbox/,/^}/p' /etc/dovecot/conf.d/10-mail.conf | egrep -v '^([ t]*#|[ t]*$)'
namespace inbox {
  separator = /
  inbox = yes
}

# doveadm -v -o imapc_user=gmailuser@example.com -o imapc_password='gmailuser_password' backup -O '-$GmailHaveLabels' -R -x 'Flagged' -x 'Important' -u gmailuser@example.com imapc:

# ls -lF /mail/example.com/data/gmailuser/Maildir/
total 112
drwx------  5 localuser  localgroup    512 Jan 13 22:45 .[Gmail].All Mail/
drwx------  5 localuser  localgroup    512 Jan 13 22:46 .[Gmail].Drafts/
drwx------  5 localuser  localgroup    512 Jan 13 22:46 .[Gmail].Sent Mail/
drwx------  5 localuser  localgroup    512 Jan 13 22:46 .[Gmail].Spam/
drwx------  5 localuser  localgroup    512 Jan 13 22:46 .[Gmail].Trash/
drwx------  2 localuser  localgroup   3072 Jan 13 22:44 cur/
-rw-------  1 localuser  localgroup      6 Jan 13 22:30 dovecot-keywords
-rw-------  1 localuser  localgroup   3684 Jan 13 22:43 dovecot-uidlist
-rw-------  1 localuser  localgroup      8 Jan 13 22:43 dovecot-uidvalidity
-r--r--r--  1 localuser  localgroup      0 Jan 13 22:30 dovecot-uidvalidity.5c3c0276
-rw-------  1 localuser  localgroup  21808 Jan 13 22:44 dovecot.index.cache
-rw-------  1 localuser  localgroup   3148 Jan 13 22:44 dovecot.index.log
-rw-------  1 localuser  localgroup    240 Jan 13 22:43 dovecot.mailbox.log
-rw-------  1 localuser  localgroup      0 Jan 13 22:30 maildirfolder
drwx------  2 localuser  localgroup    512 Jan 13 22:43 new/
-rw-------  1 localuser  localgroup    117 Jan 13 22:30 subscriptions
drwx------  2 localuser  localgroup    512 Jan 13 22:43 tmp/