private bool IsCredentialsValid(string mail, string password)
{
var relatedUserWithWebMasterRole = Optional(_intranetUserService.GetByEmail(mail))
.Filter(member => member.Role.Name == IntranetRolesEnum.WebMaster.ToString())
.Bind(member => member.UmbracoId.ToOption())
.Map(id => _memberService.GetById(id));
Option <IMember> GetUserWithMatchingEmail() => Optional(_memberService.GetByEmail(mail));
return(EnumerableExtensions
.Choose(relatedUserWithWebMasterRole, GetUserWithMatchingEmail)
.Map(user => Membership.ValidateUser(user.Username, password))
.IfNone(() => false));
}