diff --git a/alerta.conf.tmpl b/alerta.conf.tmpl
index 0ef66e8..1ad228d 100644
--- a/alerta.conf.tmpl
+++ b/alerta.conf.tmpl
@@ -20,6 +20,7 @@ mail_template = /app/email.tmpl
 mail_to = {{ env "MAIL_TO" }}
 skip_mta = False
 smtp_host = {{ env "SMTP_HOST" }}
+smtp_username = {{ env "MAIL_FROM" }}
 smtp_password = {{ secret "smtp_password" }}
 smtp_port = {{ env "SMTP_PORT" }}
 smtp_starttls = {{ env "SMTP_STARTTLS" }}