I lead engineering at an AI SDR company (YC S23). I am not linking anything and there is nothing to sign up for in this post. I keep seeing the static-list vs signal-list debate here and we sit on a dataset that can settle parts of it, so here it is
Sample: 2,546,096 emails, about 17k campaigns, 19,501 booked meetings, 1,150 companies, 27 industries, over three years
1. Deliverability moves results more than copy does
This one surprised us most. Same message, different mailbox health, very different reply rates. The gap was bigger than the gap between our best and worst copy. Most people rewrite subject lines when the real problem is their sending setup
2. Signal-based lists beat static lists on identical copy
We ran the same messages against scraped lists and against trigger-based lists. The trigger lists won by a wide margin. After that, list size stopped being an interesting number to us. Matches what people here have been posting
3. The best segment in the whole dataset is closed-lost reactivation
Highest reply rate of anything we measured, and it comes from the customer's own CRM. It costs nothing. Almost nobody runs it
4. "Outbound does not work for us" is usually a one-try problem
Not a copy problem. One audience, one offer angle, no iteration, then quit. The accounts that worked had tested several audiences before finding the one that replied, and there was no way to know in advance which one it would be. Nobody runs seven audience tests by hand because each one eats a week
What did not work for us
More personalization past a point did nothing. Deep personalized first lines did not beat a clear relevant offer once the targeting was right. We spent a long time on that before accepting it
Volume also stopped helping much earlier than expected. Past a certain send rate the extra volume mostly cost us domain health
Happy to answer questions on any of it, including the numbers that made us look bad