mod_password_policy: Change error type from 'cancel' to 'modify' This makes more sense, as the problem relates to the data that has been entered, and therefore the request could be retried with different data.

This module lets you block connections to any remote servers not on a
whitelist.

``` {.lua}
modules_enabled = {
    -- other modules --
    "s2s_whitelist",

}
s2s_whitelist = {
    "example.org",
}
```