diff --git a/notify/impl.go b/notify/impl.go
index e7739866..09c9a5b3 100644
--- a/notify/impl.go
+++ b/notify/impl.go
@@ -221,6 +221,13 @@ func NewEmail(c *config.EmailConfig, t *template.Template, l log.Logger) *Email
 // auth resolves a string of authentication mechanisms.
 func (n *Email) auth(mechs string) (smtp.Auth, error) {
 	username := n.conf.AuthUsername
+
+	// If no username is set, keep going without authentication.
+	if n.conf.AuthUsername == "" {
+		level.Debug(n.logger).Log("msg", "smtp_auth_username is not configured. Attempting to send email without authenticating")
+		return nil, nil
+	}
+
 	err := &types.MultiError{}
 	for _, mech := range strings.Split(mechs, " ") {
 		switch mech {
diff --git a/notify/impl_test.go b/notify/impl_test.go
index db46f143..bac38d81 100644
--- a/notify/impl_test.go
+++ b/notify/impl_test.go
@@ -295,7 +295,7 @@ func TestOpsGenie(t *testing.T) {
 func TestEmailConfigNoAuthMechs(t *testing.T) {
 
 	email := &Email{
-		conf: &config.EmailConfig{}, tmpl: &template.Template{}, logger: log.NewNopLogger(),
+		conf: &config.EmailConfig{AuthUsername: "test"}, tmpl: &template.Template{}, logger: log.NewNopLogger(),
 	}
 	_, err := email.auth("")
 	require.Error(t, err)
@@ -304,8 +304,9 @@ func TestEmailConfigNoAuthMechs(t *testing.T) {
 
 func TestEmailConfigMissingAuthParam(t *testing.T) {
 
+	conf := &config.EmailConfig{AuthUsername: "test"}
 	email := &Email{
-		conf: &config.EmailConfig{}, tmpl: &template.Template{}, logger: log.NewNopLogger(),
+		conf: conf, tmpl: &template.Template{}, logger: log.NewNopLogger(),
 	}
 	_, err := email.auth("CRAM-MD5")
 	require.Error(t, err)
@@ -324,6 +325,15 @@ func TestEmailConfigMissingAuthParam(t *testing.T) {
 	require.Equal(t, err.Error(), "missing password for PLAIN auth mechanism; missing password for LOGIN auth mechanism")
 }
 
+func TestEmailNoUsernameStillOk(t *testing.T) {
+	email := &Email{
+		conf: &config.EmailConfig{}, tmpl: &template.Template{}, logger: log.NewNopLogger(),
+	}
+	a, err := email.auth("CRAM-MD5")
+	require.NoError(t, err)
+	require.Nil(t, a)
+}
+
 func TestVictorOpsCustomFields(t *testing.T) {
 	logger := log.NewNopLogger()
 	tmpl := createTmpl(t)