Cold Email Infrastructure Checklist: Domains, Mailboxes and Warm-Up
Good copy fails if your emails land in spam. This checklist covers the infrastructure behind safe cold email, and how to size it for your volume.
Use separate sending domains
Send cold email from secondary domains, not your main company domain, so any deliverability problem does not affect your regular business email.
Size mailboxes and domains for your volume
A common planning assumption is around 300 emails per mailbox per day and about three mailboxes per domain. Treat the first as an upper limit, since many teams send less to protect reputation. The Outbound Meeting Math Calculator turns a revenue target into emails per day, mailboxes and domains.
Set up authentication
Configure SPF, DKIM and DMARC on every sending domain, and confirm they pass before you send. Add a custom tracking domain if your tool supports it.
Warm up before you scale
Start with low volume and increase gradually over several weeks. Keep lists verified, avoid spammy wording, and monitor bounce and complaint rates.
Monitor and retire
Watch inbox placement and bounces, pause any mailbox with problems, and rotate in fresh domains when needed.
Frequently asked questions
How many domains do I need for cold email?+
It depends on daily volume. Divide emails per day by emails per mailbox, then by mailboxes per domain. The calculator does this for you.
How long does warm-up take?+
Plan for several weeks of gradual increases before reaching full volume.
Want help with this?
Book a free 30 minute call and we will map your quickest wins across cold outbound and paid media.
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