Cold email glossary
MX record
An MX (mail exchange) record is a DNS record that tells other mail servers where to deliver email addressed to a domain. Without a valid MX record, a domain cannot reliably receive mail.
What is mx record?
When a mail server has a message for you@yourdomain.com, it queries DNS for yourdomain.com's MX records to learn which servers accept that domain's mail. Each record names a mail server and a priority number, and lower numbers are tried first, so a domain can list backups. A domain hosted on Google Workspace points its MX records at Google's servers; one on Microsoft 365 points at Microsoft's.
MX records govern inbound mail only. Outbound sending is authorized by other DNS records, mainly SPF and DKIM, which is why a domain's sending and receiving are technically independent. If a domain has no MX record at all, some servers fall back to its A record, but that fallback is unreliable and in practice a missing MX means no inbound mail.
For cold email this matters more than it first appears. A sending domain is not a send-only asset. It has to receive replies from prospects, bounce notifications from receiving servers, unsubscribe requests, and out-of-office messages. A From domain that cannot receive mail is also a classic spam pattern, and some receiving systems check for a valid MX record as a basic legitimacy signal before accepting a message.
Why it matters in cold email
A missing or broken MX record on a sending domain fails quietly. Mail still goes out, but replies bounce back to the prospects who wrote them, bounce notifications never arrive so the list never gets cleaned, and the domain looks disposable to anyone who checks. Since replies are the entire point of cold email, inbound configuration deserves the same care as the sending and authentication records.
How Sendful handles it
Every dedicated domain Sendful sets up is configured for inbound mail alongside its sending and authentication records, so replies, bounces, and unsubscribe requests all land where they should. Positive replies are routed straight to you, and bounce data feeds back into list quality.
Does an MX record affect email deliverability?
Indirectly. MX records control inbound mail, not outbound, but some receiving systems distrust a From domain with no valid MX, and without one you lose bounces and replies. Any domain used for serious sending needs working inbound mail.
Can a domain send email without an MX record?
Technically yes, since SMTP does not require the sender's domain to be able to receive mail. But every reply and bounce will fail, and the domain reads as a throwaway to filters and to anyone who inspects it. There is no good reason to run a cold email domain that way.
What should the MX record of a cold email domain point to?
The mail host where that domain's mailboxes live, typically Google Workspace or Microsoft 365. After setup, confirm with a DNS lookup that the records resolve, then send a test message to the address and make sure it arrives.
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