How many of you are using SPF or DKIM to advertise your sending mail severs?
For those who use any (or both), I'm interested in your experiences with it in general and more specific: the problems/challenges you faced during the implementation of it.
One of the problems I see for us is the fact that we do not know what ISP's send legitimate mail using our domains.
If we miss an ISP that hosts a application for us and sends mail from the app, what will be the impact?
Are there solutions to minimize the impact?