Why you got a bounce from Xmail.

What is Xmail?

Xmail is an AI-powered inbox that filters, sorts, and summarizes mail before it ever reaches a human. We run strict recipient validation: messages addressed to mailboxes that don't exist are rejected at the SMTP gate, before they enter our queue.

Common reasons your message bounced

550 5.1.1 — User unknown

The recipient address doesn't exist on Xmail. Check for typos, or confirm the address with whoever gave it to you.

454 4.7.1 — Service temporarily unavailable

Our spam-checker timed out. Your sending server should retry automatically. No action needed on your side.

451 4.7.1 — Greylist / unverified recipient

Your sending IP isn't yet trusted, or recipient verification is in progress. Retries usually succeed within minutes.

553 / 554 — Sender rejected

Your sending domain failed SPF/DKIM/DMARC, was on a public blocklist, or matched a known abuse pattern.

Legitimate misdelivery?

If you believe a real, legitimate message was rejected in error — for example, a system that's been emailing the same address for years suddenly stopped working — contact postmaster@xmail.com with the bounce text and the original SMTP transcript. We'll investigate.

Are you a spammer?

If you're sending unsolicited bulk mail to Xmail, the bounces are working as intended. Xmail strict validation, AI-powered filtering, real-time blocklists, sender reputation — none of it helps you. Stop.