Quick Answer
What should you check when an email error appears?
Copy the exact error message, identify whether the problem is connected to Mailgun or Google Workspace, and then check the matching cause. Most errors covered here involve domain verification, DNS records, provider limits, throttling, or account status.
What Email Errors Usually Mean
Email errors can appear while sending campaigns without always making the underlying problem obvious.
Most of the errors covered in this guide come from one of three areas: domain verification and DNS records, provider limitations such as rate limits or throttling, or account status issues such as permissions or termination.
Identifying which provider produced the error helps you avoid trial-and-error changes and focus on the appropriate fix.
Start with the exact message
When an error appears, copy the exact message and identify whether it involves Mailgun or Google Workspace. Then apply the matching troubleshooting guidance below.
Email Errors at a Glance
Before You Begin
Gather the information connected to the error before changing your email configuration.
- Copy the exact error message you received.
- Identify whether the sending provider is Mailgun or Google Workspace.
- If the issue involves domain verification, review the relevant DNS records.
- If DNS records are changed, allow propagation time before retesting.
Common Errors and Fast Fixes
Match the error you are seeing with the guidance below before making broader changes to your email setup.
Protect your primary inbox delivery
If your root domain already has MX records for another provider, create a dedicated sending subdomain for Mailgun so you do not disrupt the primary domain's existing inbox delivery.
Additional Notes
One MX Destination
Do not point MX records to multiple services on the same hostname.
Use a Sending Subdomain
A sending subdomain is helpful when the root domain is already being used for normal business email.
Alternative Workarounds
Some setups may use catch-all mailboxes or adjusted verification settings, depending on the sending approach.
Compare the DNS records directly
If you are unsure which DNS records are configured, review them at your DNS provider and compare them with the records required by the email provider. Retest after the changes have propagated.
Why This Matters
Fewer Failed Sends
Correct DNS records and provider verification reduce bounced or blocked email.
Better Deliverability
A properly configured sending setup helps support better inbox placement.
More Consistent Automation
Fewer sending errors help workflows and campaigns run more consistently.
Less Support Time
Identifying and correcting the underlying problem can prevent the same errors from appearing repeatedly.
Frequently Asked Questions
Why is my domain not allowed to send emails through Mailgun?
What should I do if my Mailgun account shows 'Account Terminated'?
How do I fix Mailgun Send Verification Errors?
What does 'Too Many Requests' mean?
How can I fix the '421 4.3.0 Temporary System Problem' error in Google Workspace?
Continue Learning
Continue with related email troubleshooting and sending-setup guides when you need more detailed help with provider errors, testing, or domain configuration.
