Optimizing email deliverability to Yahoo when using shared DKIM domains involves a multi-faceted approach. Core elements include strong authentication (SPF, DKIM, DMARC, double-signing), proactive sender reputation management (monitoring IPs, domain, FBLs, DMARC reports), and diligent list hygiene (segmentation, engagement-based sending, bounce processing, subscriber preference management). The inherent risks of shared DKIMs necessitate close scrutiny of domain reputation and consideration of dedicated sending infrastructure (IPs, subdomains). Sending valuable, wanted content, gradually increasing volume, and maintaining consistent sending habits contribute significantly to building a positive reputation with Yahoo, while external certifications like Return Path can provide further benefits.