We send around 600K emails a month across 17 clients, all on a pay-per-lead model. so the only metric that matters is cost per positive reply - that's how we eat.
here's the real breakdown after years of testing:
Google inboxes: 550 accounts at $3 each - $1,650 a month. 20 cold emails per inbox per day, so 242K sends. Reply rate sits at 1%, but only 5% of those are positive. That gives us 120 positive replies, costing roughly $13.75 each.
Aerosend: 420 inboxes at $2 per (negotiated hard) - $840. Same sending volume, 184.8K emails. Reply rate slightly lower at 0.9%, same 5% positive ratio, 83 positive replies at $10.12 each. best performer on pure cost.
outlook: 420 inboxes at $3 each - $1,260. Same send volume. reply rate drops to 0.6%, positive rate still 5%, so only 55 positive replies at $22.90 each. That's nearly double the cost of Google.
the key insight isn't just the numbers - it's that diversification isn't optional. When one provider gets hammered by spam filters or rate limits, you're not dead in the water if you've spread the load. Think of it like a portfolio of assets, you wouldn't put all your cash into one stock. Same logic applies to cold email infrastructure.
if anything changes I'll update. but the pattern holds: Google performs solidly, Aerosend is the value play if you can negotiate, and Outlook is the premium option that rarely justifies its cost.
