451 Temporary Local Problem

There are chances that you might have come across this issue of – “server error: 451 Temporary local problem” when you attempt to send an email to the recipient’s email address. The SMTP server of either the sender or the recipient is down which is causing this error message to appear.

With this blog, we’ll discuss in detail the cause of this error and the method to fix it. You can also follow us on LinkedIn to stay updated on the latest support articles and information we share.

Why does the “451 Temporary Local Problem” occur?

SMTP  or Simple Mail Transfer Protocol is a set of communication rules and regulations that allow the software to transmit the email on and across the server. 

The 451 temporary local problem gives an “Undelivered Send messages” error while sending mail to a client’s email address. The sender’s email client connects first to the sender’s mail server when a sender attempts to send an email and later the mail server connects to the mail server of the recipient and then transmits the mail.

Causes for getting a temporary mail delivery failure for a particular address:

  • A server down is one of the common causes for the failure of immediate message delivery.
    These temporary failures of transmission of messages mainly occur at the delivery stage and during routing as well. The delayed message or undelivered message also could occur if the DNS has failed or maybe the message has exceeded its limit.
  • Another reason for 451 Temporary local problem might be due to an update of the Exim version to a newer version, or the already working values in the Exim’s configuration were changed to invalid values that may prevent sending of emails on the server.

What is Exim?

Exim is a mail transfer agent, MTA used on a permanently internet-connected system for the increased working efficiency and for the immediate delivery of messages. It can receive mail from another host-only by using SMTP, in which addresses of both sender and client can be transferred using SMTP commands. Read how Exim sends and receives the mails for better understanding.

Routers and transports are the main delivery processing elements, commonly they are called drivers. For processing an address verification, the routers are used. Once the address is being verified by the router, it runs in “verified mode” and this never interrupts the router’s work.

But, there are a number of preconditions to be checked before running a router. The router is skipped if any one of the preconditions are not met and if every precondition is met, then the router runs. The Exim scans the address once the routing is completed and discards the repeated/ duplicated address if any.  Read to know how Exim 

The “451 temporary local problem” may occur due to the update of a newer version of Exim that caused the existing setting change and the invalid values in the already working values in the Exim’s configuration may prevent sending of emails on the server.

It can be solved by following the below-mentioned steps.

Steps to Fix “Server Error: 451 Temporary Local Problem”

  • Login to WHM
    Home » Service Configuration » Exim Configuration Manager
  • Select >> The Reset Tab
    Reset with the option >> Reset cPanel & WHM Exim configuration files, one option at a time, until the installed configuration is valid.
  •  Go to >> The Backup Tab
    Select a previous Backup >> restore

The Exim is restated and the issue is fixed in this case.


After reading the article you might have understood the reasons that can cause the “server error: 451 temporary local problem-please try later” message to appear and the possible method to fix it. Mostly it occurs when the server is loaded with exceeded limits of messages and this causes the server to slow down which affects the fast delivery of messages. But the problem may also lie in the configuration of Exim.

If you need any assistance, ServerAdminz can be of help to you. We are a premium server management and hosting support service company that offers reliable and affordable services to clients all over the world.

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