Warmup stopped: MX record errors and how to fix them

If you received an email saying warmup was paused because of an MX record error, BrandJet detected that incoming mail to your domain can no longer be delivered reliably. Warmup is paused automatically until DNS is healthy again to protect your domain reputation.

What an MX record does for warmup

Warmup works by sending and receiving low-volume conversational replies between BrandJet network of inboxes and your sending mailbox. For that loop to close, mail must reach your inbox. Your domain MX record tells the world which mail server is responsible for receiving mail. If it points to a server that will not accept your messages, the conversation breaks and warmup is paused.

Quick diagnostic

1. Open a terminal and run nslookup -type=mx yourdomain.com, or use a tool like MXToolbox.

2. Verify the result matches the provider that hosts your mailbox:

   • Google Workspace: smtp.google.com (or the older five-record pattern)

   • Microsoft 365: yourdomain-com.mail.protection.outlook.com

   • Custom provider: whatever they specify

3. Confirm there is no extra MX record from a previous provider still attached.

Common causes

• You changed mail providers and the old MX record was never removed.

• Two providers both have MX records, causing split delivery.

• A registrar imported a default MX (often mx.yourdomain.com or localhost) that does not actually receive mail.

• The MX points to a server that is rejecting mail because of an unrelated billing or quota issue at the provider.

• DNS changes have not propagated yet (allow up to 24 hours after edits).

Fix and resume

1. Update the MX record at your DNS provider so it points to the correct mail server.

2. Remove any stale MX records.

3. Wait for propagation — BrandJet re-checks every few hours.

4. Once the check passes, the warmup status returns to Healthy and resumes within a day.

5. You can also force a re-check from Warmup → your inbox → Re-check DNS.

Also recommended

While you are in DNS, verify your SPF, DKIM, and DMARC records. The same domain often has a stale SPF or missing DKIM that will quietly hurt deliverability even if MX is correct.

If MX looks fine but warmup is still paused

The error might be downstream — a mailbox-level issue like a full quota, a disabled forwarder, or an upstream filter that is bouncing warmup replies. Open a support ticket with the domain and the exact error string from the warmup dashboard and we will investigate.