diff --git a/README.md b/README.md
index 244aeb12..2465ad30 100644
--- a/README.md
+++ b/README.md
@@ -357,6 +357,13 @@ Set the message size limit for all users. If set to zero, the size will be unlim
   - drop => Drop the connection immediately with a 521 SMTP reply. Repeat this test the next time the client connects.
   - ignore => Ignore the failure of this test. Allow other tests to complete. Repeat this test the next time the client connects. This option is useful for testing and collecting statistics without blocking mail.
 
+##### DOVECOT_MAILBOX_FORMAT
+
+  - **maildir** => uses very common Maildir format, one file contains one message
+  - sdbox => (experimental) uses Dovecot high-performance mailbox format, one file contains one message
+  - mdbox ==> (experimental) uses Dovecot high-performance mailbox format, multiple messages per file and multiple files per box
+
+This option has been added in November 2019. Using other format than Maildir is considered as experimental in docker-mailserver and should only be used for testing purpose. For more details, please refer to [Dovecot Documentation](https://wiki2.dovecot.org/MailboxFormat).
 
 ## Reports
 
diff --git a/env-mailserver.dist b/env-mailserver.dist
index a3bc18f9..1e7d5f5a 100644
--- a/env-mailserver.dist
+++ b/env-mailserver.dist
@@ -216,6 +216,10 @@ DOVECOT_USER_FILTER=
 # e.g. `"(&(objectClass=PostfixBookMailAccount)(uniqueIdentifier=%n))"`
 DOVECOT_PASS_FILTER=
 
+# Define the mailbox format to be used
+# default is maildir, supported values are: sdbox, mdbox, maildir
+DOVECOT_MAILBOX_FORMAT=maildir
+
 # -----------------------------------------------------------------------------------------------------------------------------
 # ---------------- Postgrey section -------------------------------------------------------------------------------------------
 # -----------------------------------------------------------------------------------------------------------------------------
diff --git a/target/bin/delmailuser b/target/bin/delmailuser
index 8f4e0368..138ca75a 100755
--- a/target/bin/delmailuser
+++ b/target/bin/delmailuser
@@ -52,12 +52,12 @@ shift $((OPTIND-1))
         -e "s/"$USER",//g" $ALIAS_DATABASE
     [ $? = 0 ] && echo "$USER and potential aliases deleted." || errex "Aliases for $USER couldn't be deleted in $ALIAS_DATABASE. $?"
     if [ "$MAILDEL" != "y" ]; then
-      read -p "Do you want to delete the maildir as well(all mails will be removed)?(y/n) " MAILDEL
+      read -p "Do you want to delete the mailbox as well(all mails will be removed)?(y/n) " MAILDEL
       echo
     fi
-    [ "$MAILDEL" != "y" ] && errex "Leaving the maildir untouched. If you want to delete it at a later point use \"sudo docker exec mail rm -R /var/mail/${MAILARR[1]}/${MAILARR[0]}\""
+    [ "$MAILDEL" != "y" ] && errex "Leaving the mailbox untouched. If you want to delete it at a later point use \"sudo docker exec mail rm -R /var/mail/${MAILARR[1]}/${MAILARR[0]}\""
     rm -r -f /var/mail/${MAILARR[1]}/${MAILARR[0]}
-    [ $? = 0 ] && echo "Maildir deleted." || errex "Maildir couldn't be deleted: $?"
+    [ $? = 0 ] && echo "Mailbox deleted." || errex "Mailbox couldn't be deleted: $?"
   done
 
 ) 200<$DATABASE
diff --git a/target/start-mailserver.sh b/target/start-mailserver.sh
index c9e575a6..e0560530 100644
--- a/target/start-mailserver.sh
+++ b/target/start-mailserver.sh
@@ -17,6 +17,7 @@ DEFAULT_VARS["FETCHMAIL_POLL"]="${FETCHMAIL_POLL:="300"}"
 DEFAULT_VARS["ENABLE_LDAP"]="${ENABLE_LDAP:="0"}"
 DEFAULT_VARS["LDAP_START_TLS"]="${LDAP_START_TLS:="no"}"
 DEFAULT_VARS["DOVECOT_TLS"]="${DOVECOT_TLS:="no"}"
+DEFAULT_VARS["DOVECOT_MAILBOX_FORMAT"]="${DOVECOT_MAILBOX_FORMAT:="maildir"}"
 DEFAULT_VARS["ENABLE_POSTGREY"]="${ENABLE_POSTGREY:="0"}"
 DEFAULT_VARS["POSTGREY_DELAY"]="${POSTGREY_DELAY:="300"}"
 DEFAULT_VARS["POSTGREY_MAX_AGE"]="${POSTGREY_MAX_AGE:="35"}"
@@ -586,6 +587,18 @@ function _setup_dovecot() {
 	sed -i -e 's/#ssl = yes/ssl = required/g' /etc/dovecot/conf.d/10-ssl.conf
 	sed -i 's/^postmaster_address = .*$/postmaster_address = '$POSTMASTER_ADDRESS'/g' /etc/dovecot/conf.d/15-lda.conf
 
+    # Set mail_location according to mailbox format
+    case "$DOVECOT_MAILBOX_FORMAT" in
+        sdbox|mdbox|maildir )
+            notify 'inf' "Dovecot $DOVECOT_MAILBOX_FORMAT format configured"
+            sed -i -e 's/^mail_location = .*$/mail_location = '$DOVECOT_MAILBOX_FORMAT':\/var\/mail\/%d\/%n/g' /etc/dovecot/conf.d/10-mail.conf
+            ;;
+        * )
+            notify 'inf' "Dovecot maildir format configured (default)"
+            sed -i -e 's/^mail_location = .*$/mail_location = maildir:\/var\/mail\/%d\/%n/g' /etc/dovecot/conf.d/10-mail.conf
+            ;;
+    esac
+
 	# Enable Managesieve service by setting the symlink
 	# to the configuration file Dovecot will actually find
 	if [ "$ENABLE_MANAGESIEVE" = 1 ]; then