Docs Error Library Email Delivery Errors Error 450: Requested Mail Action Not Taken – Mailbox Unavailable

Error 450: Requested Mail Action Not Taken – Mailbox Unavailable

What Is Causing This Error?

‘Error 450: Requested mail action not taken – mailbox unavailable’ is a temporary error indicating that the receiving email server cannot process the email request at the moment, but it may be possible to retry later.

This issue can arise due to various reasons, such as the recipient’s mailbox being unavailable or over its storage quota, the use of greylisting as a spam prevention method, temporary network issues, server overloads, or specific policy restrictions are set by the receiving server.

While the cause of the error may vary, it typically means there’s a temporary issue with the recipient’s server or mailbox.

Resolving the Error – Solution

The initial step to fix this error is to simply wait and retry sending the email, as the error typically indicates a temporary issue. If you suspect the recipient’s email might be full or unavailable, consider reaching out to them through an alternative communication method to inform them.

If the issue is due to greylisting, it might require patience, as servers using this technique will delay the acceptance of emails from unknown senders. However, after a short period, they’ll often let the message through.

If the recipient manages their own SMTP servers, monitoring server loads and reviewing server policies can provide insights into frequent occurrences of this error.

If continuous issues arise or if the cause isn’t apparent, we recommend reaching out to the email service provider’s support team as a next step.

That’s it! Now you know the common causes of the 450 error and how to resolve it.

If you’d like to learn how to troubleshoot other common errors, check out the following tutorials: