diff --git a/friendica/content.md b/friendica/content.md
index ec28ccd90..bb858be53 100644
--- a/friendica/content.md
+++ b/friendica/content.md
@@ -96,6 +96,7 @@ The following environment variables are possible for the SMTP examples.
 -	`SMTP_FROM` Sender user-part of the address. (Default: `no-reply` - e.g. no-reply@friendica.local)
 -	`SMTP_TLS` Use TLS for connecting the SMTP Mail-Gateway. (Default: empty)
 -	`SMTP_STARTTLS` Use STARTTLS for connecting the SMTP Mail-Gateway. (Default: empty)
+-	`SMTP_AUTH` Auth mode for the SMTP Mail-Gateway. (Default: `On`)
 -	`SMTP_AUTH_USER` Username for the SMTP Mail-Gateway. (Default: empty)
 -	`SMTP_AUTH_PASS` Password for the SMTP Mail-Gateway. (Default: empty)