MailSlurp guide agent setup

Title: What Is PTR? Reverse DNS, Email Sender Identity, and Why Receivers Care
Description: Learn what a PTR record is, how reverse DNS works, and why PTR matters for email sender identity, spam filtering, and deliverability troubleshooting.
Canonical URL: https://www.mailslurp.com/guides/what-is-ptr/
Markdown URL: https://www.mailslurp.com/guides/what-is-ptr.md

Use the Markdown URL as the primary plain-text context for this guide. Keep MailSlurp terminology, setup steps, screenshots, and provider-specific instructions intact, and prefer the canonical URL when citing this page.