diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 0d5a9ca1..b69134d7 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -27,6 +27,7 @@ The development workflow is the following:
 - Code :-)
 - Add integration tests in `test/tests.bats`
 - Use `make` to build image locally and run tests
+  Note that tests work on Linux only; they hang on Mac and Windows.
 - Document your improvements in `README.md` or Wiki depending on content
 - [Commit](https://help.github.com/articles/closing-issues-via-commit-messages/), push and make a pull-request
 - Pull-request is automatically tested on Travis
diff --git a/Dockerfile b/Dockerfile
index 9a998481..64f19a38 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -97,7 +97,7 @@ RUN apt-get update -q --fix-missing && \
   rm -f /etc/cron.weekly/fstrim && \
   rm -f /etc/postsrsd.secret
 
-RUN echo "0 0,6,12,18 * * * /usr/bin/freshclam --quiet" > /etc/cron.d/clamav-freshclam && \
+RUN echo "0 0,6,12,18 * * * root /usr/bin/freshclam --quiet" > /etc/cron.d/clamav-freshclam && \
   chmod 644 /etc/clamav/freshclam.conf && \
   freshclam && \
   sed -i 's/Foreground false/Foreground true/g' /etc/clamav/clamd.conf && \
@@ -119,7 +119,8 @@ RUN sed -i -e 's/include_try \/usr\/share\/dovecot\/protocols\.d/include_try \/e
   cd /usr/share/dovecot && \
   ./mkcert.sh  && \
   mkdir -p /usr/lib/dovecot/sieve-pipe /usr/lib/dovecot/sieve-filter /usr/lib/dovecot/sieve-global && \
-  chmod 755 -R /usr/lib/dovecot/sieve-pipe /usr/lib/dovecot/sieve-filter /usr/lib/dovecot/sieve-global
+  chmod 755 -R /usr/lib/dovecot/sieve-pipe /usr/lib/dovecot/sieve-filter /usr/lib/dovecot/sieve-global && \
+  openssl dhparam -out /etc/dovecot/dh.pem 2048
 
 # Configures LDAP
 COPY target/dovecot/dovecot-ldap.conf.ext /etc/dovecot
diff --git a/target/check-for-changes.sh b/target/check-for-changes.sh
index 388f2cb3..d16aefc3 100755
--- a/target/check-for-changes.sh
+++ b/target/check-for-changes.sh
@@ -15,6 +15,16 @@ if [ ! -f postfix-accounts.cf ]; then
    exit
 fi 
 
+# Determine postmaster address, duplicated from start-mailserver.sh
+# This script previously didn't work when POSTMASTER_ADDRESS was empty
+if [[ -n "${OVERRIDE_HOSTNAME}" ]]; then
+  DOMAINNAME=$(echo "${OVERRIDE_HOSTNAME}" | sed s/[^.]*.//)
+else
+  DOMAINNAME="$(hostname -d)"
+fi
+PM_ADDRESS="${POSTMASTER_ADDRESS:=postmaster@${DOMAINNAME}}"
+echo "${log_date} Using postmaster address ${PM_ADDRESS}"
+
 # create an array of files to monitor (perhaps simple *.cf would be ok here)
 declare -a cf_files=()
 for file in postfix-accounts.cf postfix-virtual.cf postfix-aliases.cf; do
@@ -37,8 +47,11 @@ chksum=$(sha512sum -c --ignore-missing chksum)
 if [[ $chksum == *"FAIL"* ]]; then
 	echo "${log_date} Change detected"
 
+	# Bug alert! This overwrites the alias set by start-mailserver.sh
+	# Take care that changes in one script are propagated to the other
+
 	#regen postix aliases.
-	echo "root: ${POSTMASTER_ADDRESS}" > /etc/aliases
+	echo "root: ${PM_ADDRESS}" > /etc/aliases
 	if [ -f /tmp/docker-mailserver/postfix-aliases.cf ]; then
 		cat /tmp/docker-mailserver/postfix-aliases.cf>>/etc/aliases
 	fi
diff --git a/target/dovecot/10-ssl.conf b/target/dovecot/10-ssl.conf
index 5823a66d..25213a90 100644
--- a/target/dovecot/10-ssl.conf
+++ b/target/dovecot/10-ssl.conf
@@ -42,11 +42,15 @@ ssl_key = </etc/dovecot/ssl/dovecot.key
 # auth_ssl_username_from_cert=yes.
 #ssl_cert_username_field = commonName
 
-# DH parameters length to use.
-ssl_dh_parameters_length = 2048
+# SSL DH parameters
+# Generate new params with `openssl dhparam -out /etc/dovecot/dh.pem 4096`
+# Or migrate from old ssl-parameters.dat file with the command dovecot
+# gives on startup when ssl_dh is unset.
+ssl_dh = </etc/dovecot/dh.pem
 
-# SSL protocols to use
-ssl_protocols = !SSLv3,!TLSv1,!TLSv1.1
+# Minimum SSL protocol version to use. Potentially recognized values are SSLv3,
+# TLSv1, TLSv1.1, and TLSv1.2, depending on the OpenSSL version used.
+ssl_min_protocol = TLSv1.2
 
 # SSL ciphers to use
 ssl_cipher_list = ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256-SHA384:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA256
diff --git a/target/start-mailserver.sh b/target/start-mailserver.sh
index 143dc60d..e4a6fa09 100644
--- a/target/start-mailserver.sh
+++ b/target/start-mailserver.sh
@@ -95,6 +95,7 @@ function register_functions() {
 
 	if [ "$SMTP_ONLY" != 1 ]; then
 		_register_setup_function "_setup_dovecot"
+                _register_setup_function "_setup_dovecot_dhparam"
 		_register_setup_function "_setup_dovecot_local_user"
 	fi
 
@@ -1189,13 +1190,32 @@ function _setup_postfix_dhparam() {
 			notify 'inf' "Use dhparams that was generated previously"
 		fi
 
-		# Copy from the state directpry to the working location
+		# Copy from the state directory to the working location
 		rm /etc/postfix/dhparams.pem && cp $DHPARAMS_FILE /etc/postfix/dhparams.pem
 	else
 		notify 'inf' "No state dir, we use the dhparams generated on image creation"
 	fi
 }
 
+function _setup_dovecot_dhparam() {
+        notify 'task' 'Setting up Dovecot dhparam'
+        if [ "$ONE_DIR" = 1 ];then
+                DHPARAMS_FILE=/var/mail-state/lib-dovecot/dh.pem
+                if [ ! -f $DHPARAMS_FILE ]; then
+                        notify 'inf' "Generate new dhparams for dovecot"
+                        mkdir -p $(dirname "$DHPARAMS_FILE")
+                        openssl dhparam -out $DHPARAMS_FILE 2048
+                else
+                        notify 'inf' "Use dovecot dhparams that was generated previously"
+                fi
+
+                # Copy from the state directory to the working location
+                rm /etc/dovecot/dh.pem && cp $DHPARAMS_FILE /etc/dovecot/dh.pem
+        else
+                notify 'inf' "No state dir, we use the dovecot dhparams generated on image creation"
+        fi
+}
+
 function _setup_security_stack() {
 	notify 'task' "Setting up Security Stack"