diff --git a/v2/docs/guides/applications/mailcow.md b/v2/docs/guides/applications/mailcow.md
index 5b9895538..34067eae7 100644
--- a/v2/docs/guides/applications/mailcow.md
+++ b/v2/docs/guides/applications/mailcow.md
@@ -17,6 +17,15 @@ The mail server [Mailcow](https://mailcow.email/) is a dockerized application th
  - **>= 20 GB Disk**
 :::
 
+:::note Oracle Cloud Users
+**For users of OCI:** Tenancies made after June 23, 2021 are by default not allowed to send e-mail via outbound TCP port 25 to the internet.
+[OCI Docs – Outbound SMTP is blocked](https://docs.oracle.com/en-us/iaas/releasenotes/changes/f7e95770-9844-43db-916c-6ccbaf2cfe24/)
+:::
+
+## Configure Firewall
+Mailcow uses several ports including default ports for **IMAP**, **POP**, **SMTP**, etc.
+Add the [Default mailcow Ports](https://docs.mailcow.email/getstarted/prerequisite-system/#default-ports) to your [CloudPanel firewall](/docs/v2/admin-area/security/#firewall) and your host's firewall (if applicable).
+
 ## Disable Postfix 
 
 Login via **SSH** as **root** and stop and disable the **postfix** service:
@@ -121,4 +130,4 @@ To access **Mailcow** via our domain **https://mail.domain.com**, we create a [R
 
 <img alt="Mailcow Login" src={useBaseUrl('img/guides/applications/mailcow/mailcow-login.png')} />
 
-4. For security reasons, we recommend putting a [Basic Authentication](../../../frontend-area/security/#basic-authentication) in front of your **Mailcow** installation.
\ No newline at end of file
+4. For security reasons, we recommend putting a [Basic Authentication](../../../frontend-area/security/#basic-authentication) in front of your **Mailcow** installation.