The default spam settings on an agent mailbox are a guess. They might be too loose — phishing and junk land in your support agent's inbox and your model dutifully drafts a reply to a Nigerian prince. Or they're too aggressive — a customer's reply from a slightly-misconfigured small-business mail server gets flagged, and your "always reply within 5 minutes" SLA quietly breaks because the message never reached the agent.
Most people building on top of an inbox treat spam as something the provider handles invisibly, and never touch it. That's fine for a human's inbox — a human sees the spam folder, eyeballs false positives, and corrects course. An autonomous agent doesn't. It acts on what arrives, and never notices what got filtered. So the spam threshold stops being a background convenience and becomes a parameter you actually have to set per agent.
On Nylas Agent Accounts, you set it on a policy. The policy carries a spam_detection block with three knobs — a DNSBL toggle, a header-anomaly toggle, and a spam_sensitivity dial — and you attach that policy to a workspace so every agent in the workspace inherits the same spam posture. Different class of agent, different policy, different threshold. That's the whole idea, and it's what this post walks through.
