Email warmup
Also called: Warm-up, Mailbox warming
Email warmup gradually builds a sending history for a new or quiet mailbox by exchanging ordinary emails with other mailboxes that open, reply and rescue them from spam.
How it affects cold email
A brand-new mailbox that suddenly sends a lot of cold email looks like a hijacked account. Warmup, plus a slow ramp in real sending, makes the mailbox look like what it is: a person starting to use email for work.
It is not a shield. A warmed-up mailbox sending to a bad list, or misleading content, still ends up in spam.
How Inboxed handles it
- Warmup is free for every mailbox you connect, with no limit on mailboxes. Each mailbox starts at 2 warmup emails a day and adds 2 a day up to 40 by default (you can change the ramp), and keeps warming at a lower volume while campaigns send.
- Each mailbox gets a 0–100 health score: the share of its warmup emails that landed in the inbox over the last 14 days. Warmup emails never appear in the team inbox. Try the warmup tool or read how warmup works.
Related terms
Sources
Sources checked on 8 November 2026. Rules change, so check the source before you rely on a detail.
Learn more in the deliverability guide, browse the full glossary, or start free: warmup and verification cost nothing.