WhatsApp wins in Nigeria because it is where people already live daily. Data is expensive, inboxes get spammed, and many users do not check email often. WhatsApp groups feel immediate and communal, so messages get seen and forwarded fast. That said, email is still powerful for record keeping, longer content and proper segmentation. The sweet spot is to run both with clear roles. Use WhatsApp for alerts, short promos and quick polls. Use email for monthly roundups, receipts, downloads and education. Always get consent, keep groups tidy and set posting rules to avoid noise. For conversion, add trackable links and UTM tags so you see what channel drives action. Nigerian SMEs that combine WhatsApp broadcast lists with a simple email newsletter get predictable reach today and a durable database for tomorrow.