diff -up dovecot-2.3.16/doc/example-config/conf.d/10-mail.conf.default-settings dovecot-2.3.16/doc/example-config/conf.d/10-mail.conf
--- dovecot-2.3.16/doc/example-config/conf.d/10-mail.conf.default-settings	2021-08-06 11:25:51.000000000 +0200
+++ dovecot-2.3.16/doc/example-config/conf.d/10-mail.conf	2021-10-27 11:13:45.666956339 +0200
@@ -175,7 +175,7 @@ namespace inbox {
 # to make sure that users can't log in as daemons or other system users.
 # Note that denying root logins is hardcoded to dovecot binary and can't
 # be done even if first_valid_uid is set to 0.
-#first_valid_uid = 500
+first_valid_uid = 1000
 #last_valid_uid = 0
 
 # Valid GID range for users, defaults to non-root/wheel. Users having
@@ -322,6 +322,7 @@ protocol !indexer-worker {
 # them simultaneously.
 #mbox_read_locks = fcntl
 #mbox_write_locks = dotlock fcntl
+mbox_write_locks = fcntl
 
 # Maximum time to wait for lock (all of them) before aborting.
 #mbox_lock_timeout = 5 mins
diff -up dovecot-2.3.16/doc/example-config/conf.d/10-ssl.conf.default-settings dovecot-2.3.16/doc/example-config/conf.d/10-ssl.conf
--- dovecot-2.3.16/doc/example-config/conf.d/10-ssl.conf.default-settings	2021-08-06 11:25:51.000000000 +0200
+++ dovecot-2.3.16/doc/example-config/conf.d/10-ssl.conf	2021-10-27 11:13:02.834533975 +0200
@@ -3,7 +3,9 @@
 ##
 
 # SSL/TLS support: yes, no, required. <doc/wiki/SSL.txt>
-#ssl = yes
+# disable plain pop3 and imap, allowed are only pop3+TLS, pop3s, imap+TLS and imaps
+# plain imap and pop3 are still allowed for local connections
+ssl = required
 
 # PEM encoded X.509 SSL/TLS certificate and private key. They're opened before
 # dropping root privileges, so keep the key file unreadable by anyone but
@@ -64,6 +66,7 @@ ssl_key = </etc/ssl/private/dovecot.pem
 #ssl_cipher_list = ALL:!kRSA:!SRP:!kDHd:!DSS:!aNULL:!eNULL:!EXPORT:!DES:!3DES:!MD5:!PSK:!RC4:!ADH:!LOW@STRENGTH
 # To disable non-EC DH, use:
 #ssl_cipher_list = ALL:!DH:!kRSA:!SRP:!kDHd:!DSS:!aNULL:!eNULL:!EXPORT:!DES:!3DES:!MD5:!PSK:!RC4:!ADH:!LOW@STRENGTH
+ssl_cipher_list = PROFILE=SYSTEM
 
 # Colon separated list of elliptic curves to use. Empty value (the default)
 # means use the defaults from the SSL library. P-521:P-384:P-256 would be an