I have a website form that sends notification emails through Mailgun’s SMTP service. The setup uses smtp.mailgun.org on port 587 with [email protected] as the authentication username. My business email runs on Google Workspace, and form submissions should arrive at [email protected].
When visitors complete the contact form, their email becomes the sender address while [email protected] is set as the recipient. The Mailgun dashboard shows 100% successful delivery rates for all messages. However, none of these emails actually show up in my Gmail inbox or spam folder.
This means I’m missing important customer inquiries since the delivery tracking looks perfect on Mailgun’s end, but the messages vanish somewhere between their servers and Gmail. Has anyone experienced similar issues with email delivery?
Check your Mailgun logs more carefully - sometimes they show “delivered” but there’s actually a soft bounce or deferral that Gmail sends back. I’ve seen this where Mailgun thinks everything’s fine but Gmail is actually rejecting at the final step. Also try sending a test email directly from the Mailgun dashboard to see if that’s working. Might help narrow down if it’s your form code or the email setup itself.
Had this exact problem last year. Gmail’s spam filters hate when you send from visitor emails through Mailgun - the domains don’t match your auth records, so Gmail just silently drops them. Mailgun still shows delivery success, but the emails never arrive and you won’t get bounce notifications. Fixed it by switching my form to always send FROM my authenticated domain (like [email protected]) and putting the visitor’s email in Reply-To instead. Also double-check your SPF records include Mailgun’s servers. Google Workspace is way pickier about this than other email providers.
This is definitely a DMARC policy issue. Google Workspace has strict email authentication, so when you use visitor email addresses as the sender, you’re basically spoofing their domains without authorization. Mailgun might accept and process these emails, but Gmail silently rejects them during delivery. I hit the same problem with my client portal notifications. Fixed it by setting up a dedicated sending subdomain like mail.mydomain.com with its own SPF and DKIM records for proper DMARC alignment. Also check if your domain’s DMARC policy is set to “reject” - that’ll make legitimate emails vanish without a trace. Look in your Google Workspace admin console for blocked sender reports. Sometimes emails get flagged there even when they don’t show up in spam folders.