Domain age and cold email: how new is too new

A domain registered yesterday is treated by every major mailbox provider as untrusted. There is no flag, no error, no explicit penalty - just a quiet reduction in inbox placement that most operators read as a warmup problem when it is actually an age problem.

The 30-day cliff

Age is a reputation input in its own right. A domain registered days ago gives a receiver nothing to weigh, so it starts from suspicion. The steepest part of the penalty falls in the first 14 days; by day 30 the curve is flattening, and past day 90 additional age stops meaningfully helping. We do not publish a placement figure for this - InboxLee never sends and runs no fleet-wide seed tests, so there is no first-party measurement to quote.

This is independent of warmup. Warmup builds mailbox-level reputation; it does not backdate the domain. Age is its own signal, and no amount of ramping substitutes for it.

What you can do about it

• Buy domains 30 days before you plan to start sending - let them sit, then warm
• Stagger registration over months instead of buying 20 domains in one batch
• For day-one sending, use Pre-Warmed inventory - aged 3 to 12 months, with sending history
• Avoid recently expired domains with prior reputation - that history is also a signal, often a bad one

When fresh is actually fine

For a single-mailbox personal sender doing low-volume outreach, a fresh domain warmed for 14 days is workable. The age penalty is most visible at scale. If you are running 12 mailboxes across a fresh domain stack, the cumulative cost of the age penalty is meaningful. If you are sending one mailbox, you will probably never notice.