Pricing model for your outbound agency?

Which pricing model have you seen work best for cold email?

• Solely retainer
• Retainer + performance kicker
• One-time setup fee + monthly retainer + performance kicker

I’m leaning toward retainer + performance (e.g. $500+ per qualified meeting). The retainer covers fixed costs, and the performance side ties directly to outcomes, which reduces risk for the client.

Would love to know how others are structuring this and what’s actually working in practice.