diff --git a/.env.example b/.env.example
index ab7b089..4b196a6 100644
--- a/.env.example
+++ b/.env.example
@@ -28,3 +28,6 @@
 
 # Optional: This will rewrite the from address overwriting it with the specified address for all email being relayed.
 #OVERWRITE_FROM="Your Name" <email@company.com>
+
+# Optional: This will use allow you to set a custom $mydestination value. Default is localhost.
+#DESTINATION=
diff --git a/README.md b/README.md
index 0294a2c..c102581 100644
--- a/README.md
+++ b/README.md
@@ -77,6 +77,8 @@ The following env variable(s) are optional.
     OVERWRITE_FROM=email@company.com
     OVERWRITE_FROM="Your Name" <email@company.com>
 
+* `DESTINATION` This will define a list of domains from which incoming messages will be accepted.
+
 To use this container from anywhere, the 25 port or the one specified by `SMTP_PORT` needs to be exposed to the docker host server:
 
     docker run -d --name postfix -p "25:25"  \
diff --git a/run.sh b/run.sh
index 978b1f6..55ed1b1 100644
--- a/run.sh
+++ b/run.sh
@@ -30,7 +30,7 @@ DOMAIN=`echo ${SERVER_HOSTNAME} | awk 'BEGIN{FS=OFS="."}{print $(NF-1),$NF}'`
 add_config_value "maillog_file" "/dev/stdout"
 add_config_value "myhostname" ${SERVER_HOSTNAME}
 add_config_value "mydomain" ${DOMAIN}
-add_config_value "mydestination" 'localhost'
+add_config_value "mydestination" "${DESTINATION:-localhost}"
 add_config_value "myorigin" '$mydomain'
 add_config_value "relayhost" "[${SMTP_SERVER}]:${SMTP_PORT}"
 add_config_value "smtp_use_tls" "yes"
@@ -54,7 +54,7 @@ if [ ! -f /etc/postfix/sasl_passwd -a ! -z "${SMTP_USERNAME}" ]; then
   grep -q "${SMTP_SERVER}" /etc/postfix/sasl_passwd  > /dev/null 2>&1
   if [ $? -gt 0 ]; then
     echo "Adding SASL authentication configuration"
-    echo "[${SMTP_SERVER}]:${SMTP_PORT} ${SMTP_USERNAME}:${SMTP_PASSWORD}" >> /etc/postfix/sasl_passwd
+    echo "[${SMTP_SERVER}]:${SMTP_PORT} ${SMTP_USERNAME}@${DESTINATION:-localhost}:${SMTP_PASSWORD}" >> /etc/postfix/sasl_passwd
     postmap /etc/postfix/sasl_passwd
   fi
 fi