Mailbox warm-up

A brand-new domain or mailbox has no reputation, and mailbox providers treat unknown senders with suspicion. Warm-up gives it a history. Typically the mailbox starts by sending a handful of messages a day, often to a network of other mailboxes that open them, reply and move them out of spam, and the volume rises slowly over a few weeks.

Warm-up is not a way around poor practice. It builds a starting reputation, and that reputation is then kept or lost by what the mailbox sends next: verified addresses, modest daily volumes and messages people do not mark as spam. Many teams keep warm-up running at a low level alongside real outreach. Buying an older domain or a pre-warmed mailbox shortens the wait but does not change the rules that follow.

• In Outlevo: A new mailbox sends nothing until it is warm: at least 14 days, usually about 3 weeks.