Common Error Messages
This page indexes error messages you may encounter with Overton.cloud email, grouped into authentication, delivery, connection, and administrative categories—with what each means and how to resolve it.
Authentication Errors
| Error | Meaning | Fix |
|---|---|---|
550 Authentication Required | You tried to send email without proper authentication credentials. | Enable SMTP authentication in your mail client and sign in with your full email address and password. |
| Sender Verify Failed | The server could not validate that the sender’s address is legitimate on the originating server. | Confirm the sending address exists and is correctly configured on the originating mail server. |
Delivery Issues
| Error | Meaning | Fix |
|---|---|---|
550 5.7.515 Access Denied – Domain Authentication (Microsoft) | Microsoft’s servers rejected the message because SPF, DKIM, or DMARC checks failed—most commonly an incorrect DKIM record. | Verify your DKIM, SPF and DMARC records. Start with DKIM, as it is the most frequent culprit. |
| No Such Recipient Here | You sent to an address that should exist locally but doesn’t—often seen during domain transitions. | Confirm the recipient account or forwarder exists on the server and that the domain has finished migrating. |
Connection Problems
| Error | Meaning | Fix |
|---|---|---|
Temporary SMTP Blocks (554 rejections) | Automated abuse detection temporarily restricted an IP that was flooding the server—with rejected recipients, failed logins, dropped connections, or rejected messages. | These blocks lift automatically after a timeout. Fix the underlying behavior (bad credentials, invalid recipients) so it doesn’t recur. |
Temporary blocks clear themselves
If you hit a temporary 554 block, wait for the timeout rather than retrying in a loop—repeated failed attempts can extend the block.
Administrative Blocks
| Error | Meaning | Fix |
|---|---|---|
| Address Blocked by Admins | A specific email address has been blocked at the server level due to a policy violation or abuse. | Contact support to review the block and discuss reinstatement. |
Error not listed here?
Additional error documentation is on the way. If you hit an error that isn’t covered, contact support with the complete error message and a timestamp.
Need to reach us? Read Creating Effective Support Tickets first, then open a ticket at design@overton.cloud.