diff --git a/CHANGELOG.md b/CHANGELOG.md
index b39e6a67..a5d4ab30 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # Changelog
 
+## 3b7fc5930ce0b9f00f27600fbb72c3cfa3d97571 #799 (2018-02-04)
+* Introduced Postscreen
+* Breaks email submission on port 25. Sending emails should be done on port 465 or 587
+
 ## 2.0.0 (2016-05-09)
 * New version
 * Major redesign of configuration
diff --git a/README.md b/README.md
index 39a8a52a..2ef43da2 100644
--- a/README.md
+++ b/README.md
@@ -89,6 +89,17 @@ Your config folder will be mounted in `/tmp/docker-mailserver/`. To understand h
 
 `restart: always` ensures that the mail server container (and ELK container when using the mail server together with ELK stack) is automatically restarted by Docker in cases like a Docker service or host restart or container exit.
 
+#### Exposed ports
+* 25 receiving email from other mailservers
+* 465 SSL Client email submission
+* 587 TLS Client email submission
+* 143 StartTLS IMAP client
+* 993 TLS/SSL IMAP client
+* 110 POP3 client
+* 995 TLS/SSL POP3 client
+
+`Note: Port 25 is only for receiving email from other mailservers and not for submitting email. You need to use port 465 or 587 for this.`
+
 ##### Examples with just the relevant environmental variables:
 
 ```yaml