"Server response: 451 451 Temporary local - please try later" when sending email using Mailgun, Laravel and VirtualBox

Question

I am getting the error "Server response: 451 451 Temporary local problem - please try later" when sending password reminder emails via Laravel and Mailgun. I am running Laravel on VirtualBox.

I set up VirtualBox using Vagrant, would this have made a difference?

If I change the SMTP settings to my own host it works absolutely fine. Is there an issue with using Mailgun on a Virtual machine?

Update

I can send to Gmail addresses without any problems, however, they apparently are neither being blocked or allowed.

This is the error I get:

Failed: [email protected] → [email protected] Server response: 550 550
Verification failed for <[email protected]>
No Such User Here Sender verify failed

Solution

The error "451 Temporary local problem" comes from the actual mail server you are connecting to.

Typically, 451 errors are due to the receiving server rejecting your email. This can happen for a number of reasons but most likely is due to the recipients server being overloaded with messages. It can also mean that the recipients server has grey-listed the IP, and therefore delays the message until it can verify that the sending server is not trying to send spam. The receiving server may be offline as well.

Since this error message is so vague, you'll need to get more information from the recipient. I'd suggest waiting a few hours and try to send the email again.

It doesn't have to do with your Laravel installation or running with Virtualbox, further more because you tested with other SMTP settings.

Comments

[Michael]

Thank you, I'll get back in touch with my provider. (I am sending emails to myself - for testing) however I am still receiving other mail to the address in question, so as you suggest, it may be an issue with the IP)

[Paul Bele]

anytime, please let me know if you got something new on this subject :)

[Michael]

I get this error: "Failed: [email protected] → [email protected] Server response: 550 550 Verification failed for <[email protected]‌​> No Such User Here Sender verify failed" I have edited my question so to make it clearer.