Bounce error fix
Gmail refused email from your server because its IP address has no reverse DNS. Here is how to set it up.
550-5.7.25 The IP address sending this message does not have a PTR record setup, or the corresponding forward DNS entry does not point to the sending IP.
A PTR record (reverse DNS) turns your server’s IP address back into a host name. Gmail refuses mail from servers without one. This only affects you if you run your own mail server or VPS; Google Workspace, Microsoft 365 and sending tools handle it for you.
Find your sending IP. It’s in the bounce message, or in your server’s network settings.
Set the PTR record with your hosting company. Reverse DNS is controlled by whoever owns the IP, usually your VPS or server provider, not your domain’s DNS. Point it at a name like mail.yourdomain.com.
Add the matching A record. In your domain’s DNS, point mail.yourdomain.com at the same IP, so forward and reverse DNS agree.
Use the same name in your mail server’s greeting. Set the server’s host name (the HELO or EHLO name) to mail.yourdomain.com.
Check the rest of your setup
While you’re there, make sure SPF lists the server’s IP and DKIM signs its mail.
