diff --git a/core/README.md b/core/README.md
index bed1905..d941125 100644
--- a/core/README.md
+++ b/core/README.md
@@ -52,6 +52,8 @@ standard version of docker-compose.yaml from this repository.
 - `MAILMAN_REST_PASSWORD`: Which password should Core use for the REST API. If
   not defined the default is `restpass`.
 
+- `MTA`: Mail Transfer Agent to use. Either `exim` or `postfix`. Default value is `exim`.
+
 - `SMTP_HOST`: IP Address/hostname from which you will be sending
   emails. Default value is `172.19.199.1`, which is the address of the Host OS.
 
diff --git a/core/docker-entrypoint.sh b/core/docker-entrypoint.sh
index 9734ead..e6812ee 100755
--- a/core/docker-entrypoint.sh
+++ b/core/docker-entrypoint.sh
@@ -114,16 +114,7 @@ then
 fi
 
 # Generate a basic mailman.cfg.
-cat >> /etc/mailman.cfg <<EOF
-[mta]
-incoming: mailman.mta.exim4.LMTP
-outgoing: mailman.mta.deliver.deliver
-lmtp_host: $MM_HOSTNAME
-lmtp_port: 8024
-smtp_host: $SMTP_HOST
-smtp_port: $SMTP_PORT
-configuration: python:mailman.config.exim4
-
+cat > /etc/mailman.cfg << EOF
 [runner.retry]
 sleep_time: 10s
 
@@ -137,10 +128,23 @@ admin_pass: $MAILMAN_REST_PASSWORD
 class: mailman_hyperkitty.Archiver
 enable: yes
 configuration: /etc/mailman-hyperkitty.cfg
+
 EOF
 
-# Generate a basic configuration to use postfix.
-cat > /etc/postfix-mailman.cfg <<EOF
+# Generate a basic configuration to use exim
+cat > /tmp/exim-mailman.cfg <<EOF
+[mta]
+incoming: mailman.mta.exim4.LMTP
+outgoing: mailman.mta.deliver.deliver
+lmtp_host: $MM_HOSTNAME
+lmtp_port: 8024
+smtp_host: $SMTP_HOST
+smtp_port: $SMTP_PORT
+configuration: python:mailman.config.exim4
+
+EOF
+
+cat > /etc/postfix-mailman.cfg << EOF
 [postfix]
 transport_file_type: regex
 # While in regex mode, postmap_command is never used, a placeholder
@@ -148,6 +152,33 @@ transport_file_type: regex
 postmap_command: true
 EOF
 
+# Generate a basic configuration to use postfix.
+cat > /tmp/postfix-mailman.cfg <<EOF
+[mta]
+incoming: mailman.mta.postfix.LMTP
+outgoing: mailman.mta.deliver.deliver
+lmtp_host: $MM_HOSTNAME
+lmtp_port: 8024
+smtp_host: $SMTP_HOST
+smtp_port: $SMTP_PORT
+configuration: /etc/postfix-mailman.cfg
+
+EOF
+
+if [ "$MTA" == "exim" ]
+then
+	echo "Using Exim configuration"
+	cat /tmp/exim-mailman.cfg >> /etc/mailman.cfg
+elif [ "$MTA" == "postfix" ]
+then
+	echo "Using Postfix configuration"
+	cat /tmp/postfix-mailman.cfg >> /etc/mailman.cfg
+else
+	echo "No MTA environment variable found, defaulting to Exim"
+	cat /tmp/exim-mailman.cfg >> /etc/mailman.cfg
+fi
+
+rm -f /tmp/{postfix,exim}-mailman.cfg
 
 if [[ -e /opt/mailman/mailman-extra.cfg ]]
 then