What It Is
An MX record, short for mail exchange, tells other email systems where to deliver mail sent to your domain. If someone emails jane@smithplumbing.com, their mail server checks your MX records to find out which server accepts your mail. It works like a forwarding instruction at the post office that names the right mailroom. Each MX record has a priority number, and lower numbers are tried first.
Why It Matters for Your Business
MX records are why email can keep working even when your website moves, or stop working when someone edits DNS carelessly. A business switching to a new email provider must update its MX records, or new messages will keep going to the old system. Wrong MX records are one of the most common reasons a business suddenly stops getting email.
Good to Know
When changing email providers, remove the old MX records instead of leaving them alongside the new ones. Mixed records can split your mail between two systems, and some messages will seem to disappear. After the switch, send test messages from an outside address, such as a personal account, to confirm mail arrives.