greetings, Do you know why many providers even those big ones didn't implement SRS when forwarding email to other ESP?
for instance, outlook.com, mail.ru, and even google domains who has specificed email forwarding feature for their domain users, don't have SRS enabled in their forwarded messages. Since I am using SPF as a validation method, the non-srs messages from those big providers will have possibility to break SPF and be rejected by our systems. How to improve this then? Thanks.
