# methods. NFS users: flock doesn't work, remember to change mmap_disable.
#lock_method = fcntl
-# Directory in which LDA/LMTP temporarily stores incoming mails >128 kB.
+# Directory where mails can be temporarily stored. Usually it's used only for
+# mails larger than >= 128 kB. It's used by various parts of Dovecot, for
+# example LDA/LMTP while delivering large mails or zlib plugin for keeping
+# uncompressed mails.
#mail_temp_dir = /tmp
# Valid UID range for users, defaults to 500 and above. This is mostly