diff --git a/pkg/notifications/email.go b/pkg/notifications/email.go
index fdc8fee..7fb1500 100644
--- a/pkg/notifications/email.go
+++ b/pkg/notifications/email.go
@@ -64,6 +64,9 @@ func newEmailNotifier(c *cobra.Command, acceptedLogLevels []log.Level) t.Notifie
 }
 
 func (e *emailTypeNotifier) buildMessage(entries []*log.Entry) []byte {
+	// If variable SubjectTag is empty define emailSubject as "Watchtower updates".
+	// If variable SubjectTag is set define emailSubject as "$SubjectTag Watchtower updates"
+	// For example: SubjectTag=[Server Munich] -> "[Server Munich] Watchtower updates ..."
 	if SubjectTag == nil {
 		emailSubject := "Watchtower updates"
 	} else {