Everything email. One pipeline.
Free tools, practical guides and infrastructure monitoring for teams that send at scale — from 5 mailboxes to 5,000.
Diagnose problems in seconds
Domain Health Check
MX, SPF, DKIM and DMARC in one scan.
Email Header Analyzer
Trace hops and auth results.
Email Sending Calculator
Mailboxes and domains for your volume.
SPF Checker
Validate SPF and count DNS lookups.
DMARC Checker & Generator
Check or build a DMARC record.
MX Lookup
Find mail servers and the email provider.
Stop running 1,000 mailboxes from five spreadsheets
One dashboard for every sending domain and mailbox you manage. Daily checks, change detection and alerts before a broken record costs you a campaign.
- Track domains and mailbox inventory per client
- Daily SPF, DKIM, DMARC and MX monitoring with change history
- Domain expiry and blocklist alerts in Slack or email
- White-label client health reports and a full API
Learn. Analyze. Optimize. Scale.
Practical guides
Cold email, deliverability, DNS, Google Workspace and Microsoft 365 — written for people who run real infrastructure.
Read the blog →Free tools
Check records, trace headers and size your setup. No signup for basic checks — results are shareable by URL.
Browse tools →Monitor & API
Turn one-off checks into continuous monitoring across every domain, mailbox and client you manage.
Explore Monitor →Latest guides
Why Are My Emails Going to Spam? 9 Causes and Fixes
A diagnostic checklist for emails landing in spam: authentication, reputation, list quality, content and sending patterns — with free tools to check each one.
SMTP & Email InfrastructureHow Many Domains Do You Need for 1,000 Mailboxes?
Planning domains, mailboxes and costs for a 1,000-mailbox cold email operation — ratios, naming, providers and how to keep it manageable.
Cold EmailHow Many Cold Emails Can You Send Per Day?
Realistic per-mailbox and per-domain cold email limits, why provider limits are the wrong number to aim for, and how to plan volume for your team.