AEmail Deliverability Glossary

A Record

A DNS record that maps a domain name to an IPv4 address. A correctly configured A record is part of the complete DNS foundation required for email deliverability.

An A record is a DNS record that maps a domain name to an IPv4 address. It tells other servers where to find your domain.

Relevance to warm-up: During warm-up, deliverability systems check your domain's DNS configuration holistically. A missing or misconfigured A record, while not directly blocking email delivery, can signal an improperly configured domain to filtering systems. A complete, correctly configured DNS setup — including A records, MX records, PTR, SPF, DKIM, and DMARC — creates the strongest possible foundation for reputation building.

Frequently Asked Questions

Does an A record affect email deliverability?

An A record doesn't directly control email routing — that's the MX record's job — but it does affect deliverability indirectly. Receiving mail servers perform Forward-confirmed Reverse DNS (FCrDNS) checks that verify the sending IP's PTR record points to a hostname, and that hostname's A record resolves back to the same IP. If this chain is broken, many servers will reject or score the message negatively. A properly configured A record is one piece of the complete DNS hygiene that underpins warm-up success.

What DNS records are required before I start email warm-up?

Before starting warm-up you need: an A record for your sending hostname, an MX record so replies can be delivered to your domain, a PTR/rDNS record set by your hosting provider matching your sending hostname, an SPF TXT record listing authorized sending IPs, a DKIM TXT record publishing your public key, and a DMARC TXT record with at minimum p=none and a reporting address. Missing any of these weakens your warm-up results.

What is Forward-confirmed Reverse DNS and why does it matter?

Forward-confirmed Reverse DNS (FCrDNS) is a two-step check: first, a receiving server looks up the PTR record of your sending IP to find a hostname; second, it resolves that hostname's A record back to confirm it returns the original IP. When both directions match, the sender is considered properly configured. Many enterprise mail gateways and ISPs reject or heavily score-down messages from senders that fail FCrDNS. Setting this up requires coordinating with your IP provider to configure the PTR record.

Related Terms

PTR Record (Pointer Record / Reverse DNS)

A DNS record mapping an IP address back to a hostname (reverse DNS). Many receiving servers reject email from IPs without a matching PTR record.

MX Record (Mail Exchange Record)

A DNS record specifying which mail servers accept incoming email for a domain. Correctly configured MX records are required for warm-up replies to reach your inbox.

Email Infrastructure

The complete technical stack for sending and receiving email — servers, IPs, DNS, authentication protocols, and monitoring tools.

Authentication (Email Authentication)

The set of technical protocols (SPF, DKIM, DMARC) that verify a sender's identity and prove an email genuinely originated from the claimed domain.

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