Sending Domain
A sending domain is the domain name used to send cold outbound email, distinct from a company's primary website domain, chosen specifically to protect the main domain's reputation if something goes wrong with deliverability. Outbound teams typically register several sending domains and rotate mailboxes across them.
Why it matters for outbound teams
If a primary domain gets flagged for spam, it can affect not just cold outreach but every email the company sends, including invoices and customer support. Using dedicated sending domains isolates that risk. Each sending domain needs its own warmup and its own SPF, DKIM, and DMARC configuration to build reputation independently.
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Master Inbox pulls email and LinkedIn replies from every sending tool into one inbox. Free 7-day POC. Unlimited users on every plan.
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