MXToolbox

MXToolbox is a practical diagnostic toolkit for email troubleshooting, checking MX records, DNS configuration, and blacklist status all in one place. It's widely used to verify SPF, DKIM, and DMARC records and to investigate why mail isn't reaching a domain.

The tool is free and fast, making it a go-to resource for anyone dealing with delivery problems or setting up new sending infrastructure. Teams use it to troubleshoot issues quickly without needing deeper technical expertise.