451 Temporary local problem - please try later (cPanel)

451 Temporary local problem - please try later

Most often this occurs on cPanel based systems. If you do some Google searches you will see it is fairly common, but there is no single cause.

Here we will list the two most common causes where we have seen this error occur.

Cause #1

The domain name generating the error is missing from the /etc/localdomains file. We found several instances online where people state adding their domain into this file and restarting fixed the error.

Cause #2

We have observed this one first hand. There are a few criteria that must be in place for the error to occur.

1) You are using the default address (catch-all) feature of cPanel.

2) Your server is set to perform sender verification (it is on by default in cPanel). The sender verification is a server wide setting that can be controlled only through cPanel's WHM. If you do not have access to the WHM on your server you are not able to alter this value.

With both of these settings enabled the error will occur if there is a DNS problem (not able to resolve addresses) or if you receive an email from a domain that fails the sender verification test.

To fix Cause #2 you must verify your DNS is working correctly, disable the default address feature or disable the sender verification option.

To disable the sender verification you must have access to the cPanel WHM, you can find the setting located here:

WHM -> Exim Configuration Manager -> Sender Verification