Originally Posted by esmiz
Do you know if that method is 100% reliable?
Please don misunderstand me. I know that it works, but I would be more confident using it, if you can guarantee it's harmless.
using DKIM_ALWAYS is very safe because your smtp server relies on authenticated users. Although my_networks part is a strict declaration of allowed hosts/networks dkim_always allow email signing only for authenticated users which is very reliable for remote users and clients who have a dynamic ip address.
I have dkim_always on three of my servers and its all good.