Save new directories in the Maildir format in neomutt

It took me some time to stumble over this mistake, but now I'm finally
able to create new directories directly from neomutt and get them
synched correctly to the IMAP-server.
Since I use G-Mail right now that frees me from creating labels for
everything since I can now freely move my mails through the directories
and the sync will create the labels automatically.

Btw. the default is mbox as stated in the docs.

Reference: https://neomutt.org/guide/reference#3-243-%C2%A0mbox_type

.config/mutt/muttrc

@@ -12,6 +12,12 @@ set sort_aux = last-date-received
 set mailcap_path = "$XDG_CONFIG_HOME/mutt/mailcap"
 set date_format = "%d.%m.%y %I:%M"
 set index_format = "%3C %Z %d  %-30.30F  %s  (%-2.4c)"
+
+# Mandatory setting to be able to sync via offlineimap!
+# The default is mbox which is basically a file and will not be synced back to
+# the imap-server via offlineimap.
+set mbox_type=Maildir
+
 source "$XDG_CONFIG_HOME/mutt/gruvbox.muttrc"
 color index_author color167 color234
 color index_size color142 color234