Why AI SDR campaigns collapse on deliverability

Anatomy of the failure

This is the single most common way AI outbound fails, and it's the one the platforms least want to discuss. A team buys an AI SDR, the message quality is genuinely good, the first two weeks produce some replies — and then the campaign falls off a cliff. The cause is almost never the AI's writing; it's deliverability. Google and Microsoft's spam classifiers have gotten dramatically better at flagging templated cold outbound at volume, and the high send rates AI platforms encourage are exactly what triggers them. Once a domain's reputation degrades, every subsequent email lands in spam or Promotions, and the campaign produces nothing regardless of how good the copy is. The insidious part is that the platform's dashboard often still shows the emails as 'sent' and even 'delivered' — delivered to spam is still delivered — so the team keeps running a dead campaign while the metrics look superficially fine. The fix is to treat deliverability as the actual problem before scaling any AI outbound: secondary sending domains, 30+ days of warming, correct SPF/DKIM/DMARC, Google Postmaster Tools wired up, and conservative per-domain volume. The teams that get AI outbound working spend their first month on infrastructure, not on the platform's message quality. The teams that collapse are the ones who treated the platform as the whole solution and let it push volume on a domain that wasn't ready.