Postfix Gmail Bounce: This message does not have authentication information or fails to 550-5.7.26 pass authentication checks.
If you try to send email from your server using postfix without the correct SPF DNS record, it will most likely be rejected by Gmail, Outlook and other major email providers.
Free Email Forwarding Options with DigitalOcean?
How to configure Postfix to use an External SMTP Server
Can’t Send Mail to Own Domain. Postfix: status=bounced (unknown user: “user”)
How To Configure Postfix To Use Gmail SMTP on Ubuntu 22.04, 20.04, 18.04 and 16.04
How to route your PHP mail() postfix emails through Gmail's SMTP server on Ubuntu 22.04, 20.04, 18.04 and 16.04.
How To Get PHP mail() Working On Ubuntu 22.04, 20.04, 18.04 & 16.04
How-to guide for configuring postfix to work with the PHP mail() function on Ubuntu 22.04, 20.04, 18.04 and 16.04.
