An MX record (Mail Exchanger record) is a type of DNS record that tells other mail servers where to deliver email for your domain.
When someone sends an email to you@yourcompany.com, their mail server looks up the MX record for yourcompany.com to find out which server should receive the message. Without an MX record, email sent to your domain bounces.
How MX records work
The process when someone sends you an email:
- The sending server looks up the DNS record for
yourcompany.com - It finds the MX record, which points to your email host’s mail server (e.g.,
aspmx.l.google.comfor Google Workspace) - The sending server delivers the message to that mail server
- Your email host holds the message until you download it via IMAP or access it via webmail
What an MX record looks like
A Google Workspace MX record setup (added at your domain registrar) looks like:
Type: MX | Priority: 1 | Value: aspmx.l.google.com
Type: MX | Priority: 5 | Value: alt1.aspmx.l.google.com
Type: MX | Priority: 5 | Value: alt2.aspmx.l.google.com
Type: MX | Priority: 10 | Value: alt3.aspmx.l.google.com
Type: MX | Priority: 10 | Value: alt4.aspmx.l.google.com
The priority number tells the sending server which server to try first. Lower number = higher priority. Multiple records provide redundancy — if the primary server is unavailable, the sending server tries the next one.
The most common setup mistake
The most common MX record mistake is having both your registrar’s default MX record and your new host’s MX record active at the same time. This creates a split-delivery situation where some messages go to the right place and others go nowhere.
When you switch email hosts, delete the old MX records before or immediately after adding the new ones.
DNS propagation time
After you add or change MX records, the change takes time to propagate across the DNS system — typically 15 minutes to 24 hours, occasionally up to 48 hours. During propagation, some email may still go to the old records. Do not delete old mailbox data until propagation is confirmed complete.
To check propagation: dig MX yourcompany.com from a terminal, or use a tool like MXToolbox.
MX records and deliverability
MX records themselves do not directly affect inbox placement rate (IPR). They determine where email goes, not whether it lands in the inbox. IPR is affected by SPF, DKIM, and DMARC — the authentication records that prove you are authorised to send from your domain.
That said: a misconfigured MX record that causes bounces or delayed delivery will damage your sender reputation over time, which indirectly hurts IPR.
Registrar walkthroughs
For step-by-step instructions per registrar: Setting up MX records — 6 registrar walkthroughs.