I’m facing a frustrating challenge where I get a 451 Temporary local problem message whenever I attempt to dispatch password reset emails via my Laravel application using Mailgun. My setup is within a virtual machine.
Interestingly, when I switch the SMTP settings to my own host, it works flawlessly. This raises a concern about potential issues between Mailgun and my VM setup.
Emails sent to Gmail addresses go through without any trouble, but I encounter delivery issues with other domains. Here’s one example of an error I received:
I had a similar experience when I switched to a VPS. The issue stemmed from a misconfigured return path in Laravel’s mail settings. It’s crucial to ensure that your MAIL_FROM_ADDRESS in the .env file matches exactly what you’ve authorized in Mailgun, as the error indicates that Laravel may be generating bounce addresses that Mailgun cannot accept. Additionally, check that your VM’s hostname has a proper reverse DNS setup; many mail servers reject messages from servers with incorrect rDNS. A good way to troubleshoot is by testing with a basic mail function outside of Laravel; this will help you determine whether the issue lies with Laravel itself or with your VM’s Mailgun configuration.
sounds like a whitelist issue. email providers hate VM ips - they flag them as spam constantly. hit up mailgun support to whitelist your vm’s ip or ask about switching to a dedicated ip pool. dealt with the same crap on my vps last year.
The 451 error you’re experiencing, along with the sender verification issues, indicates that your domain authentication may be improperly configured with Mailgun. I encountered this situation when I transitioned to a VM setup. Typically, this relates to SPF and DKIM records that your domain lacks, which can cause receiving servers to flag your emails as suspicious. Be sure to verify your DNS settings and ensure all necessary TXT records provided by Mailgun for domain verification are present. Additionally, check that your domain displays as fully verified on the Mailgun dashboard, as it may sometimes remain in a pending state. The fact that emails to Gmail are successful, while others fail, often points to SPF or DKIM issues since Gmail tends to be more lenient with these validations. Lastly, it would be prudent to investigate if your VM’s IP address has a negative reputation, as some hosting services might utilize IP ranges that spam filters are wary of.