Free email deliverability tools: find what's hurting your inbox placement
No code. Paste a domain or email and get a clear answer in seconds.
Email deliverability tools check what mailbox providers look at before they accept your mail: SPF, DKIM and DMARC authentication, MX and reverse DNS, blocklist listings and the bulk sender rules Gmail, Yahoo and Microsoft publish. Each check here is a DNS lookup or runs in your browser, so nothing is sent from your domain.
Since February 2024 Gmail and Yahoo require bulk senders to authenticate with SPF and DKIM, publish DMARC and keep spam complaints low; Microsoft followed for Outlook.com in May 2025. The bulk sender checker tests a domain against all of it at once; the pages below cover each record on its own.
If you are fixing a problem rather than auditing, start from the evidence: paste the headers of a message that landed in spam, or decode the bounce you got back.
119 email deliverability tools
Catch-all checker
Test whether a domain accepts mail for every address by probing a random address that cannot exist.
Email header analyzer
Paste raw headers to see SPF, DKIM and DMARC results, alignment, every hop with its delay, and spam verdicts.
Deliverability audit
Audit a domain's MX, SPF, DKIM, DMARC and blocklist status in one pass, with what each result means.
SPF record generator
Build a valid SPF TXT record from the services that send for your domain, with a live count against the 10-lookup limit.
DMARC record generator
Build a DMARC TXT record with the right policy and reporting address, and see plainly when p=none enforces nothing.
MX record lookup
Free MX lookup: check the MX records for any domain and see which mail servers accept its email, in priority order, and which provider runs them.
SPF record checker
Free SPF record checker: see a domain's SPF record mechanism by mechanism, count its DNS lookups against the limit of 10, and get plain-English fixes.
DMARC record checker
Check any domain's DMARC record: see the raw TXT at _dmarc, every tag (p, sp, pct, rua, adkim, aspf) explained, and an honest grade of what it enforces.
DKIM checker
Check DKIM records on any domain, no selector needed: auto-detects common selectors, decodes key length and flags weak, revoked or broken keys. Free.
Domain blacklist check
Check if your domain is on an email blacklist: live URIBL and NordSpam DBL lookups, with Spamhaus DBL and SURBL linked, and refusals shown as unchecked.
Gmail & Yahoo bulk sender checker
One domain in, a checklist out: SPF, DKIM, DMARC, PTR and MX from live DNS, plus one-click unsubscribe, alignment and spam rate as manual items.
Reverse DNS lookup
Enter an IPv4 or IPv6 address to get its PTR hostname, plus the forward-confirm check that Gmail and Yahoo require on sending IPs.
Email provider lookup
Enter a domain or address and see its mail provider and any security gateway (Proofpoint, Mimecast, Barracuda), read from MX and SPF records.
Bounce message analyzer
Paste an Undeliverable or Delivery Status Notification email and get the code, hard or soft, the likely cause and the fix. Runs in your browser.
Spam words checker
Paste email copy to see which phrases match published SpamAssassin rules or break Google's sender guidelines, and which flags are only common advice. Runs in your browser.
Subject line tester
Preview a subject line and preheader in Apple Mail, the Gmail app and Gmail on desktop, and check it against published filter rules and Google's guidelines.
IP blacklist check
Check an IPv4 address against Spamhaus ZEN, Barracuda, SpamCop, PSBL and Mailspike, with each listing code explained and unreachable lists reported honestly.
BIMI checker
Check a domain's BIMI record, SVG Tiny PS logo, VMC or CMC certificate and DMARC policy against Google's and the BIMI Group's published requirements.
Domain age checker
Registration date, age, expiry and registrar for up to 10 domains, read from each registry's RDAP server, with honest gaps where a registry publishes nothing.
DKIM key generator
Create a 2048-bit DKIM key pair and the selector._domainkey TXT record in your browser. The private key never leaves the page.
Microsoft sender requirements checker
Check SPF, DKIM and DMARC against Microsoft's high-volume sender requirements for Outlook.com, Hotmail and Live, with its recommendations listed separately.
Microsoft 365 SMTP AUTH cut-off checker
Paste sending domains and see which run on Microsoft 365, whether SPF, DKIM and DMARC are set up for it, and what to switch to OAuth before the end of December 2026.
Bulk MX / provider lookup
Upload a CSV of emails or domains, get each row's mail provider from MX and SPF, and download the list split into Google, Microsoft and other.
List-Unsubscribe header generator
Builds the two one-click unsubscribe headers from your URL, and checks pasted headers for HTTPS, the exact Post value, a recipient token and DKIM coverage.
DNS lookup
A, AAAA, CNAME, MX, NS, TXT, SOA and CAA in one lookup, with the email records (MX, SPF, DMARC) summarised and linked to the in-depth checkers.
TXT record lookup
Shows TXT records on the domain and on _dmarc, default._bimi, _mta-sts and _smtp._tls, labels SPF, DKIM, DMARC and verification tokens, and flags duplicates.
DMARC report analyzer
Turns rua XML attachments from Google, Microsoft and Yahoo into a table of sending IPs, pass rates and unaligned senders. Unzipped in your browser.
Cold email template generator
Fill in your offer once and get three drafts (trigger-led, quick question, problem-agitate-solve and more) with subject lines. Templates, not AI.
Spintax checker
Checks {a|b} and {{RANDOM | a | b}} syntax with line and column for every error, counts the variations and shows random renders. Merge fields are left alone.
CNAME lookup
Follows the CNAME chain, checks the target against Instantly, Smartlead or lemlist, catches the doubled-domain and proxied-record mistakes, and tests HTTPS.
WHOIS lookup
Registrar, creation and expiry dates, EPP status, name servers and DNSSEC from the registry's own RDAP server, with contact records hidden until you ask.
HTML to plain text email converter
Paste HTML email source and get a readable text/plain alternative: headings, lists and links kept, pixels and hidden preheaders dropped, lines wrapped at 78.
SPF lookup counter
Expands every include and redirect, counts DNS lookups and void lookups against RFC 7208's limits, and shows which include uses the most.
DKIM signature validator
Paste a raw message to recompute the body hash and check the signature against the published key, with the reason when it fails.
Cold email subject line generator
Turns your topic, outcome and trigger into five styles of subject line, each checked against spam-filter rules and phone width.
BIMI record generator
Build the BIMI TXT record from your logo and certificate URLs, get the host name to publish it at, and check DMARC is at enforcement first.
Email size checker
Measures the HTML in KB against Gmail's roughly 102 KB clipping point, breaks down what makes it heavy, and gives you a minified copy.
MTA-STS checker
Reads the _mta-sts and TLS-RPT records, fetches the policy file over HTTPS the way a sending server does, and checks every MX host against it.
SMTP settings lookup
Detects who hosts a domain's mail from its MX records and shows that provider's SMTP, IMAP and POP settings, each from the provider's own docs.
Inbox preview: subject and preview text
Simulated Gmail, Outlook and iPhone inbox rows show where the subject and preheader get cut, and what an email's HTML puts in the preview.
Email signature generator
Fill in your details, pick a layout and colour, and copy a table-based HTML signature that pastes cleanly into Gmail, Outlook and Apple Mail.
DNS propagation checker
Asks 12 public DNS-over-HTTPS resolvers and the zone's own name server for one record, shows each answer as it came back, and how long each cache keeps an old one.
SPF flattener
Resolves every include, a and mx in an SPF record to the ip4 and ip6 ranges behind them, outputs the flattened record (split into sub-records when it's too long) and warns that it goes stale.
MX records generator
Pick Google Workspace, Microsoft 365, Zoho, Fastmail or iCloud+ and a DNS host; get the MX, SPF, DKIM and DMARC records from the provider's own guide, ready to paste.
Mailto link generator
Type the address, subject and message and copy a mailto: link that opens a ready-to-send draft, as a plain link, HTML or Markdown. Spaces and line breaks are encoded the way RFC 6068 asks.
TLS-RPT record checker
Enter a domain to read its _smtp._tls TXT record, validate it against RFC 8460 (case-sensitive tags, one record only) and check that every mailto: or https: destination can receive reports.
BIMI SVG validator and converter
Paste or upload an SVG to check it against the SVG Tiny PS profile and Gmail's requirements, then download a converted copy with before and after previews. Runs in your browser.
Bulk domain availability checker
Paste up to 100 domains (500 when signed in), or bare names to try across .com, .io and other TLDs, and see which are registered and which look available, straight from each registry's RDAP server.
Bulk SPF, DKIM and DMARC checker
Paste a list of domains and see, for each one, whether SPF, DKIM, DMARC and MX are published, with a pass, warn or fail and the reason in plain English.
Bulk DNS lookup
Paste a list of domains or host names and get their A, AAAA, MX, TXT, NS and CNAME records side by side, in one table and one CSV.
Bulk website status and parked domain checker
Paste a list of domains and see each one's HTTP status, where it redirects, and whether it looks parked or for sale, with the signal that says so.
Company name to domain finder
Paste company names and get the likely domain for each, with high, medium or low confidence and the reason, from Wikidata and a check of the home page.
Domain to company name lookup
Paste domains or work email addresses and get the company or site name for each, with high, medium or low confidence, the source and the mail server.
Email spoofing test
Enter a domain, or a list, and get a plain yes, partly or no from its DMARC and SPF records, with what to change to stop forged mail.
DKIM selector finder
Enter a domain and see which of about 80 known DKIM selectors it publishes, with each key's length and the sending platform where DNS shows it.
Bulk catch-all checker
Paste domains or email addresses and see, for each domain, whether its mail server accepts a made-up address: catch-all, not catch-all or unknown, with the reason.
Email stack lookup
Paste company domains and see each one's mailbox provider, sending platforms, security gateway, DMARC reporting and verified SaaS, with the DNS record behind each.
Domain drop date calculator
Enter a domain or a list. Each one's registry status and expiry date give its phase and the window in which it could be deleted and released.
Bulk nameserver lookup
Paste domains and get each one's NS records with the company that runs them (Cloudflare, Route 53, GoDaddy, Namecheap and about 40 others), plus parked domains, in one table.
Which ESP sent this email?
Paste the raw headers of any email and see the platform that sent it, such as SendGrid, Mailchimp or Amazon SES, with the DKIM, bounce and Received lines behind it.
Cold email domain finder
Enter your main domain, such as acme.com, and get lookalike sending-domain ideas like getacme.com, tryacme.com, acmehq.com and acme.io, each checked against the registry for likely availability, plus the SPF, DKIM and DMARC setup checklist.
Cold email domain checker
Paste the domains you just bought and get a pass/fix checklist for each: mailbox provider, MX, SPF (with the 10-lookup count), DKIM, DMARC, age and website, plus copyable records for Google Workspace, Microsoft 365 or Zoho.
Domain email setup checker
Paste the domain you just bought, or up to 25, and get a pass/fix checklist for MX, SPF, DKIM and DMARC with the mailbox provider named and the exact records to copy for Google Workspace, Microsoft 365 or Zoho.
Professional email address generator
Enter your name and your new domain to get professional address ideas (first@, first.last@, hello@, support@) with the reason to pick each, plus the postmaster@ and DMARC aliases worth creating.
Website host checker
Paste one website or a list and see which platform serves each one, the DNS record or header that says so, plus the company running its DNS and its email.
Domain registrar lookup
Enter a domain or a list and get each one's registrar and expiry from the registry, the company that runs its DNS (where records are edited) and its email provider.
SPF record merger
Paste your SPF records or enter a domain and get one merged record with duplicates removed, one ending, the DNS lookup count and 255-character strings ready to publish.
Email forwarding checker
Enter a domain, or up to 25, and see from its MX records whether mail goes to a forwarding service, a mailbox provider or nowhere, with the SPF include and DMARC it needs.
Lookalike domain checker
Enter your domain to generate up to 150 typo, homoglyph, Unicode and TLD variants and see which are registered, which answer on the web and which have MX records to send or receive email.
MTA-STS generator
Enter your domain, pull in your MX hosts and pick a mode to get the mta-sts.txt policy file, the _mta-sts TXT record and a matching TLS-RPT record, checked against RFC 8461.
Is Gmail down?
Reads Google's own status feed for open Gmail incidents and connects to Gmail's mail servers to read their greeting, with the time of each check. Outlook.com too, from Microsoft's status page.
UTM builder
Paste a URL, pick an email or SMS preset and get a tagged link that GA4 counts in the right channel. Tag hundreds of URLs at once and download them as a CSV.
EML viewer
Drop an .eml file to read it: sender, recipients, date, the HTML and text versions, attachments to download and the raw headers. Remote images stay blocked until you allow them.
Bulk domain age checker
Paste or upload a list of domains or emails and get each domain's creation date, age and registrar from RDAP, sorted, filtered by age and downloadable.
Bulk domain expiry checker
Paste or upload a list of domains and get each one's expiry date, days left and registrar from RDAP, grouped into expired or in grace, under 30 days, 30–90 days and 90+ days.
Available domain name generator
Enter up to three keywords and pick TLDs: name ideas from prefixes, suffixes and keyword joins are checked against each registry's RDAP server and DNS, likely-available first.
Bulk WHOIS lookup
Paste or upload domains and get registrar, created, updated and expiry dates, EPP status codes, nameservers and DNSSEC for each, from the registry's RDAP server, in one table.
Domain extension checker
Type one name and check it across up to 52 extensions in five groups (popular, tech, business, brand and country), with each registry's answer: likely available, registered or unknown.
Domain hack generator
Enter words or a brand name and see every way the word's ending can be a domain extension (market.ing, brew.ing, delicio.us), each checked against its registry: likely available, registered or unknown.
Domain transfer checker
Paste domains and see which can move to another registrar now, which need the registrar lock turned off, which are inside the 60-day window (with the date it ends) and which are blocked by the registry.
Bulk SSL certificate checker
Paste domains or host names and get each one's TLS certificate: days left, expiry date, issuer, the names it covers, and whether it's expired, for the wrong name or not trusted.
DNSSEC checker
Paste one domain or a list and see which are signed and validate, which are broken (validating resolvers refuse them), which have keys but no DS at the registry, and which aren't signed.
CAA record checker
Paste domains or host names and see, for each, the CAA record a CA would use (its own or a parent's), the CAs allowed for ordinary and wildcard certificates, and where refusals are reported.
IPv6 checker
Paste domains and see, for each, whether the website (the domain and www), the MX mail servers and the name servers publish IPv6 addresses: IPv6 ready, Partly or IPv4 only.
Domain status code checker
Paste domains and get every EPP status code in each registry record, explained: who set it, what it does, and what to do, with each domain read as Normal, Needs a look, On hold or Being deleted.
Security headers checker
Paste websites and see, for each home page, whether Strict-Transport-Security, Content-Security-Policy, clickjacking protection and nosniff are set, and which are weak.
Robots.txt checker
Paste websites and see, for each, whether robots.txt lets Googlebot, Bingbot and the main AI crawlers (GPTBot, ClaudeBot, PerplexityBot, CCBot...) fetch the home page, plus its Sitemap lines.
Sitemap checker
Paste websites and see, for each, where its sitemap is (robots.txt or /sitemap.xml), whether it's a sitemap or an index, how many URLs it lists and whether it's over the limits.
Favicon checker
Paste websites and see, for each, the favicon and Apple touch icon its home page declares (or /favicon.ico), whether each loads as an image, and its format and size.
Bulk SPF lookup counter
Paste domains and see, for each, how many DNS lookups its SPF record costs out of 10, the includes that cost the most, void lookups and faults that make SPF fail.
Punycode converter
Paste domains with accents or non-Latin letters, or xn-- names, and get both forms, the length DNS sees, and warnings for invalid characters and mixed scripts.
Security.txt checker
Paste websites and see, for each, whether /.well-known/security.txt exists, has the required Contact and Expires fields, hasn't expired and follows RFC 9116, with every contact listed.
Ads.txt checker
Paste publisher domains and see, for each, whether /ads.txt exists, how many DIRECT and RESELLER records it has, which ad systems it names, its OWNERDOMAIN and MANAGERDOMAIN, and every line a buyer's crawler will skip.
Llms.txt checker
Paste websites and see, for each, whether /llms.txt exists, whether it's Markdown with the H1, blockquote summary and linked H2 sections the llmstxt.org proposal describes, how many links it lists, and whether /llms-full.txt exists.
WWW redirect checker
Paste domains and see, for each, where http://, https://, http://www. and https://www. end up, the redirect codes on the way, and whether the site is Consistent, uses temporary redirects, has one version that fails, is split into two copies, or doesn't send visitors to HTTPS.
Bulk SOA record lookup
Paste domains and get each zone's SOA record: primary name server, hostmaster address, serial (and whether it reads as a date), refresh, retry, expire and the negative-caching TTL, with timers outside the RFC 1912 and RFC 2308 suggestions flagged.
TLD registry lookup
Paste extensions, domains or URLs and see, for each top-level domain, its sponsoring organisation and technical contact's organisation from IANA's root zone records, when it entered the root, whether it's DNSSEC-signed, and whether its registry offers RDAP for domain lookups.
Email domain health checker
Runs MX, SPF (with the 10-lookup count), DKIM, DMARC, MTA-STS, TLS-RPT, BIMI and blocklist checks on one domain and returns a score out of 100 with the fixes in the order to make them.
Email deliverability checklist
18 items across authentication, reputation, list hygiene, volume, content and unsubscribe, each tied to Google, Yahoo, Microsoft or the law. Five run as live checks on your domain; the rest you tick off.
Bounce Doctor
Sorts every bounce in a pasted batch of NDRs or a CSV export into bad address, missing domain, sender block, security gateway or temporary, explains each code in plain English and builds suppress, retry and review files.
Merge tag converter
Rewrites the personalization tags in a template for Instantly, Smartlead, lemlist, Mailchimp, HubSpot, Brevo, Klaviyo or a Google Sheets mail merge: standard fields to the tool's own names, other fields as custom variables, fallbacks kept where the tool's syntax has one, spintax and unsubscribe tags left alone.
Personalization line builder
Builds a new column from up to five if-then rules and a default line: "if title contains founder", "if recent_post is filled", "if industry is SaaS". Each line uses {{column}} tags from your CSV, and a rule only fires when every field it uses has a value, so no row gets "Saw is hiring". Templates and rules, not AI.
Feedback-ID header generator
Builds Feedback-ID: a:b:c:SenderId from up to three identifiers (campaign, customer, mail type) and a SenderId, or reads one you already send, and checks it against Google's rules: SenderId 5-15 characters, colons only as separators, identifiers not repeated across fields, no per-message values such as addresses or UUIDs.
ESP suspension appeal builder
Builds a plain reply to an ESP account review or suspension from what you tick: the cause, where contacts come from, changes already made, numbers removed and remaining, and how they prevent a repeat. Follows the structure Amazon SES, HubSpot and Mailgun publish, warns about purchased lists and planned-not-done steps, and says where each platform takes the reply.
Bulk DNS records for cold email domains
Paste your sending domains, pick Google Workspace or Microsoft 365 and your DNS host, and get MX, SPF, DKIM, DMARC and an optional Instantly, Smartlead or lemlist tracking CNAME for every domain, as one CSV or zone-file lines.
Custom tracking domain generator
Pick Instantly, Smartlead, lemlist or another tool and paste your sending domains. Get the CNAME host and target from the tool's own help article for each domain, formatted for your DNS host, plus the exact value to paste back into the tool.
Email obfuscator
Five copy-paste snippets for one address, optional link text and subject: split address with the mailto set on hover, focus or tap; link built by JavaScript with an [at] [dot] fallback; HTML-entity mailto; written-out text; CSS-reversed text. Each says what it stops and what it costs visitors.
HTML email checker
Reads the HTML you paste and flags what the big clients drop or mangle: scripts, forms, external stylesheets, flexbox and grid, CSS variables, SVG and WebP images, base64 images, relative image paths, unclosed table tags, missing doctype or charset, and size past Gmail's 102 KB clip.
Email accessibility checker
Checks a pasted HTML email against the WCAG basics that apply to email: a lang attribute, layout tables marked role="presentation", alt text that isn't a file name, links that say where they go, heading order, text under 14px and inline colour contrast below 4.5:1.
Email CSS inliner
Writes each <style> rule into the style attribute of every element it matches, in cascade order (specificity, source order, !important), keeps existing inline styles, leaves media queries, @font-face and :hover rules in the head, and can copy pixel widths to width attributes for Outlook.
Email footer generator
Builds a footer from your business name, postal address, an unsubscribe URL or your platform's merge tag (Mailchimp, HubSpot, ActiveCampaign, SendGrid), an optional preferences link, reason line, contact address and ad notice, as table-based HTML and plain text, then runs it through the CAN-SPAM checks.
Email link checker
Lists every link in a pasted email with its text and target, and flags URL shorteners, text that shows one domain but links to another, empty or # links, relative links, bare IP addresses and plain http, plus every domain the email links to.
Email image to text ratio checker
Counts the images in a pasted email against its visible text in bytes and words, names the SpamAssassin HTML_IMAGE_ONLY band it falls in (under 3,200 bytes of text with images), and flags missing alt text, base64 and http images, tracking pixels and hidden text.
CAN-SPAM compliance checker
Checks a pasted email for an unsubscribe link or merge tag (or a reply-only opt-out), a physical postal address (street, P.O. box or postcode), a subject without a fake Re: or Fwd:, a From name that identifies you and CASL's contact-method rule; the rules it can't read from text are listed for you to confirm.
HELO hostname checker
Enter the HELO/EHLO name (or paste a Received header) and the sending IP: checks the name is a real FQDN, has an A record pointing at the IP, the IP's PTR resolves back, and the PTR matches the HELO, as Spamhaus's sender guidelines ask.
Send schedule planner
Takes your list, your sender inboxes and a daily cap per inbox (with an optional warm-up ramp), and gives every row a send date and a sender, skipping weekends and holding back extra contacts at the same company to another day.
Bulk mailbox CSV generator
Takes your sending domains, the sender names and the address formats you want (jane@, jane.doe@…), and writes one row per mailbox in the CSV format each admin console's bulk upload takes, with random passwords for Google made in your browser.
Spam trap risk checker
Nine questions about where your list came from and how you maintain it give an exposure level and a fix for each risky habit. A self-assessment: no tool can name which addresses are traps.
DMARC alignment checker
Compares the From domain with the SPF (Return-Path) and DKIM (d=) domains under relaxed or strict alignment, and shows whether the message passes DMARC. Paste headers to fill it in. Runs in your browser.