> For the complete documentation index, see [llms.txt](https://docs.emaildelivery.com/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.emaildelivery.com/docs/what-you-need-to-know-before-you-install-velocity-mta/sending-domain-and-ptr-must-match.md). # Sending Domain and PTR must match {% hint style="info" %} Make sure you read [PTR Records and Reverse DNS](/docs/what-you-need-to-know-before-you-install-velocity-mta/ptr-records-and-reverse-dns.md) before this page. {% endhint %} Always use subdomains in your MTA configuration. If your domain is bobshotdogs.com, and your IP address is 1.2.3.4, create a DNS A record called velocity.bobshotdogs.com pointing to 1.2.3.4. Next, open a support ticket with the owner of your IP addresses, usually your VPS hosting provider, and ask for a PTR record to be created for IP address 1.2.3.4 with hostname velocity.bobshotdogs.com. When you add your Velocity MTA server in the UI, make sure you specify the correct DNS records you just created. The Header Domain A record and PTR record for the IP set by the hosting provider must match.