Deliverability Guard — know the moment your email breaks
Since late 2025, Google and Microsoft reject bulk email outright when a domain's SPF, DKIM, or DMARC is missing or broken — and a single blacklist listing can silently send every message you send to spam. Deliverability Guard watches your domain around the clock and emails you in plain English the moment something changes, with a link that explains exactly how to fix it.
What it watches
Blacklist listings
Your sending IP is checked against major DNS blacklists (Spamhaus, SpamCop, Barracuda, SORBS). The moment it appears on one, you get an alert — before your customers notice missing mail.
Email authentication
SPF, DMARC, MTA-STS and TLS-RPT records are fingerprinted on every check. If a record changes or disappears — a registrar migration, a DNS mistake, an expired include — you know immediately.
SSL certificates
Certificate expiry is tracked with a configurable warning window, so a forgotten renewal never takes your site (or your mail server's TLS) down.
DNS records
Any A, AAAA, CNAME, MX, NS or TXT record can be watched for changes — catch hijacked nameservers, broken MX swaps, or an accidental record deletion.
DMARC report ingestion Pro+
Point your domain's rua= at your private ingest address and the
unreadable XML reports become one table: who is sending as your domain,
pass rates per source, and a plain-English "safe to move to p=quarantine?" advisor.
Branded client reports Agency+
Create read-only domain-health report links with your name, colour and logo on top — always live data, one-click print-to-PDF. Built for agencies and MSPs sending monthly check-ins to clients.
How it works
- Add a domain. No credit card; the free tier doesn't even require an account — just an email address and a confirmation click.
- We check continuously. Daily on the free tier, hourly on Pro, every 15 minutes on Agency and Scale.
- You get a plain-English alert. Not a wall of JSON — what broke, why it matters, and a link to the matching free tool and guide to fix it.
- History accumulates. Every check is recorded, so you can show exactly when an issue started and when it was resolved.
Pricing
All ~97 free tools on this site stay free and unlimited forever — plans gate only continuous monitoring depth and API access. Annual billing is roughly two months free.
Free
$0
- 1 domain
- Daily checks
- All 4 monitor types
- Email alerts
- 7-day history
- No account required
Pro
$19/mo
or $190/yr
- 5 domains
- Hourly checks
- All 4 monitor types
- DMARC report ingestion + enforce advisor
- Email alerts
- 90-day history
Agency
$59/mo
or $590/yr
- 25 domains — built for agencies & MSPs
- Checks every 15 minutes
- All 4 monitor types + DMARC ingestion
- Branded client report links (print-to-PDF)
- Email alerts
- 1-year history
Scale
$149/mo
or $1,490/yr
- 100 domains
- Checks every 15 minutes
- Full REST API access (all 5 endpoints, 1,500 req/min)
- 2-year history
Prefer to talk to a human first? Send us a message and we'll set you up. Developers: the REST API is documented on the API reference.
On the roadmap
Coming next, not yet available — listed so you know where the product is heading, not to sell you something that doesn't exist yet:
- Webhook alerts — push monitor events into Slack or your own systems.
- Benchmark context everywhere — "your config beats X% of the domains we scan" on every monitor, powered by our quarterly research dataset.
Frequently asked questions
Why do I need monitoring if I can just run the free checks?
You can — and they stay free. The difference is when you find out. A blacklist listing or a deleted DMARC record costs you with every hour it goes unnoticed; monitoring turns "we found out when customers complained" into an email within the check interval.
What happens when an alert fires?
You get a plain-English email naming the domain, what changed, the previous and current state, and a link to manage the monitor. No app to install, no dashboard you have to remember to look at.
Can I cancel anytime?
Yes. Plans are month-to-month (or annual, your choice) and you can cancel from the billing page; your monitors simply fall back to the free tier's limits.
Do you gate any of the free tools behind a plan?
No, and we never will. The ~97 web tools are free and unlimited without an account. Plans pay for continuous monitoring depth (more domains, faster checks, longer history) and API automation.
How this tool works: This tool runs in your browser and on our server in real time. Depending on the tool, results are computed directly from the input you provide or retrieved from live, authoritative data sources at the moment you run a lookup. We do not sell your data, and your lookups are kept private — any history shown here is stored only on your device.