Troubleshooting SMTP Responses

Troubleshooting SMTP Response 455 (Temporary Error)

What causes SMTP 455 error and how do you fix it? SMTP code 455 is used to indicate a temporary issue with the server, where it suggests retrying the request at a later time.

What causes the 455 SMTP error

SMTP code 455 is used to indicate a temporary issue with the server, where it suggests retrying the request at a later time. This code usually implies a transient condition which is expected to be resolved after some delay.

SMTP 455 error explained

Let's break down the SMTP 455 error code into it's parts:

4 The first digit of the SMTP 455 indicates whether the response is good, bad or incomplete. 4xx Transient Negative Completion.
5 The second digit of the SMTP 455 indicates the response category. x5x replies generally indicate the status of the mail system or mail server status.
5 The third digit of the SMTP 455 indicates the specific response. While not always true, 0 tends to be a generic response and other numbers are more specific.

SMTP 455 error code examples

  • 455 4.4.5 Try again later

What causes the SMTP 455 error?

  • Server temporarily unable to handle the request due to overload, updates, maintenance, or other transient issues.

How do you fix an SMTP 455 error?

To address a 455 error:

  • Simply wait for a while and then retry sending the email.
  • If the issue persists, consider checking with the server administrator for any ongoing server issues or maintenance activities.
  • Ensure that your email client or server is not repeatedly and rapidly sending requests, which could exacerbate the server load.

Need help sending or receiving transactional email? Contact CloudMailin Support to see if we can provide a more reliable SMTP service.


Other SMTP Responses

Troubleshoot other SMTP responses using the links below: