As part of a system-wide optimization of email security performance, Sender ID is no longer offered in Email Deliverability settings
Why: For Salesforce orgs created in Winter ’25 or later, Sender ID compliance cannot be enabled in Email Deliverability Settings. Technological enhancements and operational efficiency simplify email authentication processes and replaced Sender ID functionality. This change is a result of RFC7208 (Request for Comments), published in 2015
How: If you’re using Sender ID, you don’t need to make any changes. Integrations that use Sender ID continue to work after Summer ’24. Sender ID records are identified by their v=spf2.0 prefix. A record that starts with this prefix can’t be used
