The outbound deliverability crisis is domain reputation collapse from AI SDR email volume, capping 47% of deployments in the first 90 days. The leak sits upstream of the buyer — teams optimise send volume while inbox placement is nobody’s owned responsibility.
The numbers behind the crisis
41% of enterprise B2B teams now run at least one AI SDR in production, up from 12% a year ago. Per-rep outbound volume has jumped 6.4x. Reply rates have fallen 38%, from 4.7% to 2.9%. And 47% of AI SDR deployments get capped by domain reputation collapse in the first 90 days — with Microsoft 365 inboxes applying the strictest filtering. You can send all the AI-personalised emails you like. If they land in spam, they don’t exist.
Why this is a handoff problem
This looks like an infrastructure problem. It’s really an ownership problem — and ownership problems are handoff problems.
SDR teams are measured on sends, meetings booked, and pipeline created. Those are their metrics. So they optimise send volume. Deliverability infrastructure — domain warming, sender reputation management, DKIM and SPF rotation, inbox placement monitoring — doesn’t sit on any SDR’s scorecard. It sits in the gap between marketing ops, IT, and the SDR team. Nobody owns it. Everybody assumes somebody else does.
The handoff here isn’t between two people. It’s between two metrics: send volume, which someone is accountable for, and inbox placement rate, which nobody is. The leak happens in that unowned gap — upstream of the buyer, before a sales handoff ever gets a chance to happen.
How this tends to play out
A mid-market SaaS team deployed two AI SDR agents across three sending domains. In the first six weeks, send volume climbed fast — exactly what the SDR team was incentivised to produce. But nobody had set up proper domain warming or monitored inbox placement. Microsoft 365 flagged one domain within weeks; by week eight, all three domains were hitting spam folders at an estimated 70% rate. The SDR dashboard showed sends up 6x. The pipeline dashboard showed meetings down. Nobody connected the two because inbox placement wasn’t a metric anyone was watching.
The fix
Stop measuring send rate. Start measuring inbox placement rate — the percentage of your emails that actually reach the inbox, not the spam folder. Tools like Smartlead and Instantly can report this at the domain level. Assign ownership of deliverability to a named person, not a committee. Build a rotation schedule for sending domains. Warm new domains before putting volume through them. And cap send volume per domain based on placement rate, not on SDR ambition.
If 47% of deployments fail in 90 days, the problem isn’t the AI. It’s the unowned handoff between the people who send and the infrastructure that delivers.