Missing emails in 250ok seed lists are a multifaceted problem typically stemming from a combination of technical issues, list management practices, and sending configurations. Primarily, seed lists are either not being sent to correctly, are suppressed due to segmentation, engagement filters, or unsubscribes, or are being inadvertently removed due to poor seed list hygiene. Maintaining good seed list hygiene, isolating the seed list, validating addresses, and regularly monitoring performance are key to resolving these issues and ensuring accurate deliverability metrics. Proper placement of seed list emails and reviewing suppression lists are also vital.