Question 1

What is an MX record?

Accepted Answer

An MX (Mail Exchanger) record specifies the mail servers responsible for accepting email on behalf of a domain. Each MX record has a priority value — lower numbers have higher priority. For example, priority 10 is tried before priority 20. If the primary server fails, email falls back to lower-priority servers.

Question 2

Why is my email not being delivered?

Accepted Answer

Common causes: (1) Missing MX records — run an MX lookup to verify they exist. (2) MX hostname doesn't resolve to a valid IP. (3) Mail server is offline or port 25 is blocked by a firewall. (4) Your sending IP is on a blacklist. (5) SPF/DKIM/DMARC authentication failures causing rejection.

Question 3

Should I have multiple MX records?

Accepted Answer

Yes, for redundancy. Configure a primary MX with a low priority number (e.g., 10) and a backup MX with a higher priority (e.g., 20). If the primary server is unreachable, sending servers will retry delivery to the backup. Many ESPs (Google Workspace, Microsoft 365) automatically configure multiple MX records.