Summary
Emailing password reminders via Laravel on VirtualBox using Mailgun returns a 451 error, yet direct SMTP through my host works. See error:
ErrCode: 550 — Bounce rejected for <[email protected]>
I ran into similar issues with Mailgun and Laravel running on VirtualBox a year ago. My problem turned out to be a mismatch between the sender domain configured in Laravel and the authorized domains in Mailgun. The networking configuration of VirtualBox sometimes affects how external services validate the source of requests. After I corrected the envelop sender settings in Laravel and verified that Mailgun had the right domain settings, the errors stopped occurring. I also reviewed Mailgun’s logs to confirm that no additional authorization issues were flagged during sending.
I encountered a similar problem where the settings on my virtual machine were not fully compatible with Mailgun’s requirements. After some investigation, I found that adjusting the sender configuration in Laravel to match the domain verified in Mailgun was essential. Re-examining how the network is configured in VirtualBox also helped, as sometimes NAT or bridged mode settings can cause unexpected behavior. Reviewing SPF and DKIM records was also part of the troubleshooting process. I suggest double-checking these aspects, as they have proven to be the root cause in my experience.