"Access denied" when using contributor account to access to content-type

When I was using the contributor account to check the content-type folder is "message" or "Dicussion", I got an error: "Access denied!"

My code:

if (ctype.ResourceFolder.Name == "Message")
{
     //do something
}

But nothing happened with owner account.

Yes, because contributor account can not access to ResourceFolder properties of content-type. ResourceFolder was inherited from SPFolder and execute the method FolderEnsure. You know to give the access to folder ensure the account must be set the properties currentWeb.AllowUnsafeUpdates = true; and the default for member account does not have permission to run that update.

You can change the code to look like this:

if (ctype.Id == SPBuiltInContentTypeId.Message)
{
    //do something
}

The result is nearly the same.