Yahoo has made its email validation policy stricter, as part of an effort to stop spoofing attacks on Yahoo email addresses. However, the new policy is hurting the workflow on legitimate
mailing lists. The issue stems from a new DMARC (Domain-based Message Authentication, Reporting and Conformance) policy for third-parties.
The new specification brings about the idea of aligned identifiers, which requires the SPF or DKIM validation domains to be the same as or sub-domains of the domain for the email address in the “from” field.