How do mailbox providers treat cold vs warm email?

Mailbox providers treat cold and warm email differently based on the relationship signals they can observe.

Warm email advantages:

Previous engagement creates positive reputation

Recipients' actions (opens, replies, moves from spam) build trust

Contact lists and address books signal expected mail

Consistent sending history establishes patterns

Cold email challenges:

No prior relationship to evaluate

Competing against actual spam that's also unsolicited

First messages must earn trust with no history

Any negative signals (complaints, ignores) have outsized impact

How filtering differs:

Unknown senders face higher content scrutiny

Low engagement from cold sends damages reputation quickly

Warm senders get benefit of the doubt; cold senders don't

Authentication matters more when no relationship exists

Practical implications:

Cold email needs better targeting to generate engagement

Technical setup must be perfect (no authentication failures)

Volume must be conservative until reputation establishes

Every early message matters more than in established programs