diff --git a/models/user_mail.go b/models/user_mail.go
index 7244ec378..8bf74b81b 100755
--- a/models/user_mail.go
+++ b/models/user_mail.go
@@ -293,6 +293,16 @@ func MakeEmailPrimary(email *EmailAddress) error {
 	}
 
 	user.Email = email.Email
+
+	has, err = sess.Where("id!=?", user.ID).
+		And("type=?", user.Type).
+		And("email=?", strings.ToLower(user.Email)).
+		Get(new(User))
+	if err != nil {
+		return err
+	} else if has {
+		return ErrEmailAlreadyUsed{user.Email}
+	}
 	if _, err = sess.ID(user.ID).Cols("email").Update(user); err != nil {
 		return err
 	}
diff --git a/routers/user/setting/account.go b/routers/user/setting/account.go
index 27f0bf1c8..6165bfc5b 100644
--- a/routers/user/setting/account.go
+++ b/routers/user/setting/account.go
@@ -80,6 +80,12 @@ func EmailPost(ctx *context.Context, form auth.AddEmailForm) {
 	// Make emailaddress primary.
 	if ctx.Query("_method") == "PRIMARY" {
 		if err := models.MakeEmailPrimary(&models.EmailAddress{ID: ctx.QueryInt64("id")}); err != nil {
+			if _, ok := err.(models.ErrEmailAlreadyUsed); ok {
+				ctx.Flash.Error(ctx.Tr("form.email_been_used"))
+				ctx.Redirect(setting.AppSubURL + "/user/settings/account")
+				return
+			}
+
 			ctx.ServerError("MakeEmailPrimary", err)
 			return
 		}