What deliverability depends on
Deliverability is not one number. A message can be accepted by the receiving server and still land in spam, and the reason can sit in several places at once. Good email deliverability monitoring software watches each layer, because a fix in one place does nothing if the problem is in another.
- Blacklists. 109 DNS lists, from Spamhaus ZEN and DBL to Barracuda, SpamCop and UCEPROTECT.
- Authentication. SPF, DKIM and DMARC records, plus MX, PTR, BIMI, MTA-STS and TLS-RPT.
- Who sends as you. DMARC aggregate reports show every ESP, CRM and server using your domain, and whether each one passes.
- Reputation at the big providers. Google Postmaster Tools, Microsoft SNDS and Yahoo signals, connected from your own accounts.
- Spam rate. Alerts when your Gmail user-reported spam rate crosses 0.1 percent and again at 0.3 percent.
- Inbox placement. Seed tests that show inbox, spam or missing at Gmail, Outlook, Yahoo and others.
The rules mailbox providers enforce today
Since February 2024, Google and Yahoo require bulk senders (roughly 5,000 or more messages a day to their users) to authenticate with SPF and DKIM, publish a DMARC record that aligns with the From domain, offer one-click unsubscribe on marketing mail, keep a valid PTR record, and keep the user-reported spam rate under 0.3 percent, ideally under 0.1 percent. In May 2025 Microsoft added similar rules for Outlook.com, Hotmail and Live: high volume senders need SPF, DKIM and DMARC, or their mail goes to junk and then gets rejected.
Monitoring turns those rules into checks you can see. Each domain gets a Domain Health score from 0 to 100, and each finding is a sentence with the fix, such as "SPF uses 12 DNS lookups (limit 10), receivers return permerror". Our bulk sender requirements checklist explains each rule in detail.
How to check deliverability by hand
That routine works for one domain if someone remembers to do it. It does not scale to ten brands, and it misses the problem that starts on a Friday night. Our free email deliverability test covers the first two steps in one go, and monitoring repeats them all on a schedule.
- 1 Look up your SPF, DKIM and DMARC TXT records and count the SPF DNS lookups. More than 10 is a permanent error under RFC 7208.
- 2 Check every sending IP and domain on the main blacklists.
- 3 Log in to Google Postmaster Tools and Microsoft SNDS and read the reputation and spam rate graphs.
- 4 Send a test to a few personal mailboxes at different providers and note where it lands.
- 5 Repeat every week, and again after any DNS change or new sending tool.
Run a free check on your own domain or IP, then keep it monitored.
Check NowHow BlacklistMonitoring compares
Several good tools cover parts of this. The table below uses each vendor's public pages at the time of writing. Prices and features change, so check their sites before you decide.
| Tool | Main focus | Blacklist coverage | Price from |
|---|---|---|---|
| BlacklistMonitoring | Blacklists, authentication, DMARC reports, reputation and inbox placement in one panel | 109 lists, checks every 5 to 60 minutes | $49/mo, $24/mo billed yearly |
| MxToolbox | DNS and blacklist tools | Both paid plans capped at 5 domains | Free weekly monitoring for 1 domain, paid $129 or $399/mo |
| GlockApps | Inbox placement testing | Through IP reputation monitors only | $59 to $129/mo |
| EmailGuard | Cold email senders | Weekly automated blacklist checks | $49 to $199/mo |
| EasyDMARC | DMARC first | Deliverability features sold through sales | See vendor site |
Alerts that say what to do
Every alert names the asset, the change and the next step. A Spamhaus listing links to its removal steps. A DMARC record that disappeared after a DNS migration says which record and what to publish. A Gmail spam rate at 0.12 percent tells you to look at your last campaigns before you hit the 0.3 percent line.
Alerts go to email and Slack on every plan, and to Microsoft Teams and webhooks from Business up. Business also sends a weekly digest, so quiet weeks still leave a record. Checks are DNS only: we never send mail from your domain or to it.
Plans for every sending setup
Starter at $49 a month covers 10 domains and IPs with hourly checks, DMARC reports up to 50,000 messages a month and removal instructions. Business at $149 adds 15-minute checks, sender source discovery, reputation signals, spam rate alerts and 50 inbox placement tests a month. Agency adds client workspaces and white label reports, and Scale adds CIDR ranges, a REST API and SSO. Yearly billing halves each price.
If DMARC is your main concern, start with DMARC monitoring. If listings are, read about blacklist monitoring.
Frequently asked questions
What is email deliverability monitoring?
It is ongoing tracking of the factors that decide inbox or spam: blacklists, authentication records, mailbox provider reputation, spam rate and inbox placement. It alerts you when one of them changes, instead of waiting for open rates to fall.
What is a good email deliverability rate?
Most healthy senders see 95 percent or more of mail accepted and a large majority placed in the inbox. The spam rate matters more than any single number: keep it under 0.1 percent at Gmail and never above 0.3 percent.
How do I monitor my sender reputation?
Connect Google Postmaster Tools for Gmail and Microsoft SNDS for Outlook.com, and watch blacklists for your IPs and domains. BlacklistMonitoring shows those signals together from the Business plan.
Is MxToolbox enough for deliverability monitoring?
MxToolbox is a solid DNS and blacklist tool. Its Delivery Center plans cost $129 and $399 a month and both cover 5 domains, so senders with many domains, or who also want DMARC reports, reputation signals and placement tests in the same view, often pair it with other tools or use one platform that covers all layers. See our MxToolbox alternative comparison.
Does monitoring send any email from my domain?
No. Blacklist and DNS checks are lookups only. Inbox placement tests use a message you send yourself to our seed addresses, so nothing goes out in your name without your action.