We check every signal so you don’t have to guess.
Most senders find out about a deliverability problem when revenue drops. SenderDirect exists to move that moment earlier: free, professional-grade diagnostics and plain-English guides for anyone who sends email, from a solo founder to an enterprise team.
How we build
Show the evidence
Every result shows the raw record we read and the rule it was judged against. No black-box scores.
No account
No signup, no email gate, no trial. Type a domain and get the answer.
Nothing stored
Checks run in your browser through public DNS-over-HTTPS resolvers. We never see what you look up.
Free for good
The tools and the guides stay free. Deliverability basics should not sit behind a paywall.
How the Sender Reputation Score works
Four weighted categories, each scored 0 to 100, blended into one grade. We only use signals anyone can verify in public DNS. Engagement and complaint data stay private to each mailbox provider, so read the score alongside Google Postmaster Tools and Microsoft SNDS.
| Grade | Score | Meaning |
|---|---|---|
| A | 90 to 100 | Excellent |
| B | 75 to 89 | Good |
| C | 60 to 74 | Fair |
| D | 40 to 59 | Poor |
| F | 0 to 39 | Critical |
Authentication
SPF validity and lookup count, DKIM key presence and strength across 25 common selectors, and DMARC policy, coverage and reporting.
Blocklists
The IPs behind your MX hosts and apex domain, checked against 15 public DNS blocklists. A single listing costs real points.
DNS health
MX records and redundancy, reverse DNS with forward confirmation on mail server IPs, and nameserver count.
Infrastructure
DNSSEC, MTA-STS, TLS-RPT, BIMI and distinct mail exchangers: the signals of a sender who maintains their setup.
What we publish
Beyond the ten tools, we maintain six pillar guides, a bounce code reference and a blog with platform comparisons, warmup schedules and benchmark roundups. Our comparisons are based on hands-on use, public documentation and published pricing, and we update them when vendors change plans.
Who writes our comparisons
Our platform comparisons are written by Yevhen Kralych, a product data analyst and SEO lead with more than a decade in email and marketing automation software.
Get in touch
Found a record we misread, or a bounce code we should cover? We read everything. Write to hello@senderdirect.online or use the contact page.
Check your domain before you hit send.
Run the full check: SPF, DKIM, DMARC, 15+ blocklists, MX, reverse DNS and infrastructure, scored A to F with a ranked list of fixes.