Domain Blacklist Check
Check whether a sending domain or its mail servers appear on email blocklists.
Email Header Analyzer
Trace an email's delivery path, per-hop delays and SPF/DKIM/DMARC results. Runs in your browser.
MX Lookup
List a domain's mail servers in priority order and check for common MX misconfigurations.
SMTP Test
Connects to an SMTP server, performs EHLO, and optionally STARTTLS.