What does Risky mean?

Risky is not invalid — it is a real mailbox with a caution flag. Here is how to handle it.

A risky verdict means the receiving server gave us reason to believe the mailbox exists, but with a signal that sending might not go smoothly. It is deliberately separate from undeliverable: deleting every risky address throws away real subscribers, and blasting all of them at once risks bounces.

What triggers it

• Mailbox full — the account exists but is over quota right now; often temporary.
• Greylisting — the server deliberately delays first-time connections. We retry and wait; when the answer arrives late but positive, the address resolves as risky rather than a clean deliverable.
• Soft rejections and throttling — the server answered evasively or slowed us down instead of giving a clean yes.

What to do with risky addresses

Do not blanket-delete them. Send to risky segments in smaller, spaced batches, watch the bounce rate, and let engagement decide: an address that opens is proven; one that hard-bounces removes itself. If your sender reputation is fragile, hold risky addresses until your deliverable segment has warmed your domain.