MM-58255 Ensure remote users do not get valid email addresses (#27421)

* remote users don't get valid email addresses; remote users cannot have access tokens

* block notification emails for remote users

---------

Co-authored-by: Mattermost Build <build@mattermost.com>

server/public/model/user.go

@@ -346,7 +346,7 @@ func (u *User) IsValid() *AppError {
 		}
 	}
 
-	if len(u.Email) > UserEmailMaxLength || u.Email == "" || !IsValidEmail(u.Email) {
+	if len(u.Email) > UserEmailMaxLength || u.Email == "" || (!IsValidEmail(u.Email) && !u.IsRemote()) {
 		return InvalidUserError("email", u.Id, u.Email)
 	}
 

server/public/model/user_test.go

@@ -9,9 +9,10 @@ import (
 	"strings"
 	"testing"
 
-	"github.com/mattermost/mattermost/server/public/shared/mlog"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+
+	"github.com/mattermost/mattermost/server/public/shared/mlog"
 )
 
 func TestUserDeepCopy(t *testing.T) {
@@ -117,6 +118,13 @@ func TestUserIsValid(t *testing.T) {
 	user.LastName = ""
 	require.Nil(t, user.IsValid())
 
+	user.Email = NewId()
+	appErr = user.IsValid()
+	require.True(t, HasExpectedUserIsValidError(appErr, "email", user.Id, user.Email), "expected user is valid error: %s", appErr.Error())
+
+	user.RemoteId = NewString(NewId())
+	require.Nil(t, user.IsValid())
+
 	user.FirstName = strings.Repeat("a", 65)
 	appErr = user.IsValid()
 	require.True(t, HasExpectedUserIsValidError(appErr, "first_name", user.Id, user.FirstName), "expected user is valid error: %s", appErr.Error())