Three separate questions
MX concerns receiving mail. SPF concerns permitted sending sources. DMARC concerns handling messages that cannot authenticate the visible author domain through aligned SPF or DKIM. A domain may send email without accepting incoming messages.
Using the check
Enter the exact domain used for email, such as example.com. The tool queries DNS from Düsseldorf, displays records and explains findings. Green indicates plausible checked settings, yellow guidance or incomplete checks, and red a detected configuration problem. Read the explanation alongside the color.
Limits of the results
The check sends no email. DKIM inspects a public key, not a message signature. STARTTLS optionally checks up to two public mail targets on port 25. A positive result establishes neither inbox delivery nor every sender configuration.