Sending domain

A sending domain is a domain used only for outbound email, set up separately from a company's primary domain so that the reputation risk of cold outreach never touches the domain that carries client email, invoices, and support.

The rule is simple: never send cold email from the domain your business runs on. A spam complaint against outreach is a marketing problem. A spam complaint against your primary domain is a business problem, because it puts your invoices and your client correspondence at risk.

So outreach runs on separate domains that look like yours. If the company is acmeindustrial.com, the sending domains might be acmeindustrial.co, getacmeindustrial.com, and acme-industrial.com. Each gets its own SPF, DKIM, and DMARC, its own warmup, and two to four mailboxes. If one gets a bad reputation, it's retired and the others keep sending.

The domains should be registered in the client's name, not the agency's. When the program ends, the client keeps them, along with the deliverability history.

An example

A distributor with six branches runs outreach on five sending domains with three mailboxes each, fifteen mailboxes in all, each sending 20 to 40 emails a day. That's a few hundred emails a day across the territory, which is what a signal-based list produces. The company's primary domain sends nothing but order confirmations and invoices, same as before.

How many you need

Three to six for most programs. It's set by the volume the list produces divided by 20 to 40 emails per mailbox per day, with a spare domain or two so one can be rested without stopping the program.

Related terms

Email warmup · SPF, DKIM, and DMARC · Domain reputation · Email deliverability

If you want this run for you, see our cold email agency, or cold email for industrial distributors.