diff --git a/README.md b/README.md
new file mode 100644
index 0000000..799d60e
--- /dev/null
+++ b/README.md
@@ -0,0 +1,74 @@
+[Roundcube](https://roundcube.net/) webmail interface with postgres backend.
+
+## Environment Variables
+### DOMAIN
+Space seperated list of domains to listen to.
+
+### DB_USER
+Name of the database user.
+
+### DB_PASSWORD
+Password for the database user.
+
+### DB_HOST
+Database host.
+
+### DB_NAME
+Database name.
+
+### LDAP_HOST
+Ldap host to connect to for password changes.
+
+### LDAP_HOST
+- default: 389
+
+Port of the ldap host.
+
+### LDAP_STARTTLS
+- default: true
+
+Whether to use starttls when connecting to the ldap host.
+
+### LDAP_BASE_DN
+Base DN on the ldap host.
+
+### LDAP_USER_DN_MASK
+How user DNs look like.
+
+### LDAP_PASSWORD_ATTRIBUTE
+- default: userPassword
+
+How is the ldap attribute for the user password called.
+
+### IMAP_HOST
+- default: tls://%n
+
+IMAP host to authenticate users against.
+
+### SMTP_HOST
+- default: tls://%n
+
+SMTP host for sending mails.
+
+### SMTP_PORT
+- default: 587
+
+Port for the SMTP host.
+
+### SECRET_KEY
+Secret key for session secrets.
+
+### CIPHER_METHOD
+- default: AES-256-CBC
+
+Encryption algorithm for session secrets.
+
+## Ports
+- 80
+
+## Capabilities
+- DAC_OVERRIDE
+- NET_BIND_SERVICE
+- SETGID
+- SETUID
+