Email Deliverability Tools We Tested for Inbox Placement (2026)
Ten tools, five problems they actually solve. We tested seedlist inbox placement, DMARC report viewers, blacklist monitors, warmup networks, and DNS auditors so you can pick the right layer for your sending program. Listed alphabetically for fair evaluation.
lightbulbKey takeaways
- arrow_rightNo single tool covers every deliverability layer. Most sending programs end up running two or three: one for inbox placement testing, one for DMARC and blacklist monitoring, and one for warmup.
- arrow_rightFor seedlist inbox placement testing, GlockApps and Mailmodo are the standouts. GlockApps has the broader seed network, Mailmodo bundles it with a marketing platform.
- arrow_rightFor DMARC reporting and blacklist monitoring, Validity Everest is the enterprise standard, Suped is the lightweight modern alternative, and MXToolbox still wins on free one-off checks.
- arrow_rightFor warmup, MailReach runs a clean dedicated network. Smartlead bundles warmup into its sending platform, which is more practical if you also need an outbound tool.
- arrow_rightFor transactional sending, Postmark has the best reputation by design. Mailgun, SendGrid, and MailerSend are stronger on scale and integrations.
- arrow_rightMailsfinder is on this list because our free deliverability checker audits MX, SPF, DKIM, and DMARC for any domain in seconds. It does not do warmup, seedlist tests, or blacklist monitoring. Use it as the first 5-minute check before you pay for anything heavier.
- arrow_rightStart with free tools (DNS audit, MXToolbox check, GlockApps free test). Layer in monitoring only after you know your baseline.
The five layers of email deliverability
Every tool on this list owns one or two of these layers. None owns all five. Knowing the layers is the only way to choose the right stack instead of buying overlapping subscriptions.
DNS audit
MX, SPF, DKIM, DMARC records. Catches misconfigurations.
Seedlist placement
Where one test email actually lands across Gmail, Outlook, Yahoo.
DMARC reports
Aggregate XML reports parsed into who is sending as you.
Blacklist monitoring
Continuous checks across 100+ RBLs with alerting.
Inbox warmup
Automated peer-to-peer exchanges to build sender reputation.
Jump to a tool
Listed alphabetically. No ranking, just what each one is built for.
Feature matrix
Which tool does what. Read across, not down.
| Tool | Warmup | Seedlist test | DMARC reports | Blacklist monitor | DNS audit |
|---|---|---|---|---|---|
| GlockApps | no | yes | yes | yes | yes |
| MailerSend | no | no | partial | no | basic |
| Mailgun | no | no | partial | partial | basic |
| Mailmodo | no | yes | no | partial | basic |
| MailReach | yes | yes | no | partial | basic |
| Mailsfinder | no | no | audit only | no | yes (free) |
| MXToolbox | no | no | yes | yes | yes |
| Postmark | no | no | yes (DMARC Digests) | partial | yes |
| SendGrid | no | no | partial | partial | basic |
| Smartlead | yes | partial | no | no | basic |
| Suped | no | no | yes | yes | yes |
| Validity Everest | no | yes | yes | yes | yes |
Partial = available but limited. Basic = surface-level check only. Audit only = static DNS read, no aggregation.
GlockApps
SEEDLIST INBOX PLACEMENTBuilt for one job and good at it: tell you where your email actually lands. GlockApps maintains a seedlist of real inboxes across Gmail, Outlook, Yahoo, AOL, Apple Mail, and regional providers, then reports placement per provider in a single dashboard. The platform has expanded into DMARC reporting and blacklist monitoring, which makes it a reasonable single-vendor option for teams that do not want to stitch three tools together. Pricing starts at $59/month for the Basic plan with 5 seedlist tests. Try the free single test at glockapps.com.
Key features
Inbox placement across 90+ provider seeds
Spam content scoring and SpamAssassin breakdown
DMARC report aggregation with daily digests
Blacklist monitoring across major RBLs
Pros
- check_circleLargest seedlist of any tool tested
- check_circleBundles three deliverability layers
- check_circleFree single test on signup
Cons
- cancelCheap plans cap tests too tightly
- cancelNo warmup network
- cancelDashboard UI feels dated
"GlockApps is the only tool we trust for seedlist data. We run a test before every major launch." Real user review placeholder, source: G2.
MailerSend
TRANSACTIONAL ESPSister product to MailerLite, MailerSend is a transactional sending platform with a generous free tier (3,000 emails/month) and a clean developer experience. Deliverability is not its primary marketing pitch but the platform exposes domain verification, SPF/DKIM setup wizards, suppression management, and per-domain reputation views. Good fit for SaaS products that want reliable transactional sending without paying for a top-tier ESP. See plans at mailersend.com.
Key features
3,000 emails/month free, $35 for 50K
Domain authentication wizard and inbound routing
Suppression lists with bounce categorization
Drag-and-drop template editor
Pros
- check_circleMost generous free tier of any ESP
- check_circleClean API and webhook setup
- check_circleBacked by MailerLite infrastructure
Cons
- cancelNo seedlist or DMARC tooling
- cancelShared IP reputation can vary
- cancelSupport response slower than Postmark
"MailerSend got us off SendGrid with a 70% cost cut and identical deliverability." Real user review placeholder, source: G2.
Mailgun
DEVELOPER-FIRST ESPOwned by Sinch, Mailgun is the long-running developer-first transactional ESP. The deliverability layer is anchored by Mailgun Optimize, a paid add-on that bundles seedlist testing, inbox placement reports, DMARC monitoring, and address validation. The base sending product gives you per-domain reputation, suppression management, and detailed log retention. Strong fit for engineering teams that want one vendor for sending plus deliverability analytics. Pricing starts at $35/month for 50K emails. See mailgun.com.
Key features
Mailgun Optimize add-on for seedlist and DMARC
Detailed delivery logs (up to 30 days)
Dedicated IP and IP warmup automation
Inbound parsing and routing
Pros
- check_circleMature API with strong docs
- check_circleOptimize bundles deliverability tooling
- check_circleReliable at high volume
Cons
- cancelOptimize is a separate paid add-on
- cancelPricing climbs fast above 100K/mo
- cancelShared IPs require careful sender hygiene
"Mailgun Optimize replaced two separate vendors for us. The DMARC view alone justified the upgrade." Real user review placeholder, source: G2.
Mailmodo
MARKETING ESP + INBOX SPAM TESTMailmodo is primarily an AMP email marketing platform, but the team ships a free Inbox Spam Test tool that runs seedlist placement across Gmail, Outlook, Yahoo, and AOL. It is genuinely useful as a standalone test even if you do not use the broader Mailmodo product. The marketing platform itself runs from $99/month with interactive AMP email support and journey builders. Use the free seedlist tool at mailmodo.com/inbox-spam-test.
Key features
Free seedlist inbox test (no signup)
AMP for Email interactive campaigns
Journey builder and segmentation
Deliverability consultancy included on higher plans
Pros
- check_circleFree seedlist test is genuinely useful
- check_circleAMP email differentiates from peers
- check_circleHands-on deliverability help included
Cons
- cancelNo DMARC report aggregation
- cancelPlatform cost is high if you only want testing
- cancelSeed network smaller than GlockApps
"The free Mailmodo seedlist test caught a spam folder issue our ESP missed for weeks." Real user review placeholder, source: G2.
MailReach
DEDICATED WARMUP NETWORKMailReach focuses entirely on inbox warmup and inbox placement testing. The warmup network exchanges friendly conversations between real inboxes, with replies, marks-as-important, and folder moves designed to mimic genuine engagement. Spam Test Pro runs seedlist tests against 20+ providers. Strong fit for teams running cold or transactional mail from new domains or domains recovering from a reputation hit. Plans start at $25/month per inbox for warmup. See mailreach.co.
Key features
Warmup network with human-style replies
Spam Test Pro seedlist across 20+ providers
Reputation tracking dashboard per inbox
Works with any mailbox (Google, Outlook, custom SMTP)
Pros
- check_circleCleanest dedicated warmup network
- check_circlePer-inbox reputation reporting
- check_circleWorks alongside any sending platform
Cons
- cancelPer-inbox pricing adds up fast
- cancelNo DMARC or blacklist monitoring
- cancelWarmup networks debated by some experts
"MailReach got our new domain to 95% inbox placement in three weeks." Real user review placeholder, source: G2.
Mailsfinder
FREE DNS DELIVERABILITY AUDITFull disclosure: Mailsfinder is the publisher of this guide. Our core product is an email finder and verifier, not a deliverability platform. That said, our free deliverability checker audits MX, SPF, DKIM, and DMARC records for any domain in seconds, and is genuinely useful as a first check before you pay for anything heavier. Use it to confirm your sending domain is set up correctly. Do not use it instead of a real seedlist test or DMARC report viewer. Tool lives at mailsfinder.com/tools/deliverability-checker.
Key features
Free MX, SPF, DKIM, DMARC record audit
Plain-language fix suggestions per misconfiguration
Bundled with email verification (99% accuracy)
100 free credits per day, no card needed
Pros
- check_circleFree and instant DNS health snapshot
- check_circlePairs with email verification in one workflow
- check_circleNo signup wall on the audit tool
Cons
- cancelNo warmup network of any kind
- cancelNo seedlist or inbox placement test
- cancelNo blacklist monitoring or DMARC aggregation
"Ran the Mailsfinder DNS audit and found a missing DKIM record in 30 seconds. Saved us a paid audit." Real user review placeholder, source: G2.
MXToolbox
DNS + BLACKLIST INDUSTRY STANDARDTwenty years old and still the first tool most deliverability engineers reach for. MXToolbox provides free one-off DNS checks, blacklist lookups across 100+ RBLs, SMTP diagnostics, and a SuperTool that runs combined queries. Paid plans add continuous monitoring with alerts and DMARC reporting. The product is utilitarian rather than beautiful, which is the point. See mxtoolbox.com.
Key features
Free blacklist check across 100+ RBLs
SuperTool for combined DNS, SMTP, blacklist queries
Continuous monitoring with alerting (paid)
DMARC reporting on higher plans
Pros
- check_circleFree tools are best in class
- check_circleTrusted by IT and email admins
- check_circleBroad RBL coverage
Cons
- cancelInterface feels dated for marketers
- cancelContinuous monitoring jumps in price
- cancelNo seedlist or warmup features
"MXToolbox SuperTool is muscle memory at this point. First check on every domain issue." Real user review placeholder, source: G2.
Postmark
TRANSACTIONAL ESP, BEST DELIVERABILITYOwned by ActiveCampaign, Postmark has earned its reputation by being aggressive about who is allowed to send. They actively reject marketing mail on transactional servers, run separate IP pools for the two stream types, and publish ongoing delivery time benchmarks. The platform also runs free DMARC Digests, a no-friction way for any domain to start collecting DMARC reports without signing up for sending. Pricing starts at $15/month for 10K emails. See postmarkapp.com.
Key features
Separate transactional and broadcast streams
Free DMARC Digests for any domain
45-day message retention with full event log
Public delivery time benchmarks
Pros
- check_circleStrict policy keeps IPs clean
- check_circleFree DMARC Digests are excellent
- check_circleGenuinely helpful support team
Cons
- cancelPricier per email than Mailgun or MailerSend
- cancelNot suitable for cold outreach (TOS)
- cancelNo native seedlist testing
"Switched from SendGrid to Postmark. Bounce rate dropped, delivery time halved, support actually responds." Real user review placeholder, source: G2.
SendGrid
SCALE ESP (TWILIO)Now Twilio SendGrid, this is the highest-volume transactional and marketing ESP in the list. The free tier covers 100 emails/day forever. Paid plans add dedicated IPs, IP warmup automation, and Email Validation API credits. Expert Insights is a paid managed deliverability service for high-volume senders. Strong fit for product engineering teams that already use Twilio, or any team sending above 1M emails/month. See sendgrid.com.
Key features
100 emails/day free forever
Dedicated IPs with automated warmup
Expert Insights managed deliverability add-on
Email Validation API for list hygiene
Pros
- check_circleHandles highest send volumes reliably
- check_circleTwilio platform integrations
- check_circleGenerous free tier for prototyping
Cons
- cancelShared IP reputation can be rough
- cancelSupport is slow on lower plans
- cancelMarketing UI separate from API product
"SendGrid scales to anything we throw at it, but we had to pay for dedicated IPs to fix deliverability." Real user review placeholder, source: G2.
Smartlead
OUTBOUND PLATFORM + WARMUPSmartlead is a cold email sending platform with warmup baked in. Unlimited warmup is included on every plan, which is unusual and one reason it has taken share from per-inbox warmup tools. The platform also handles unlimited mailbox rotation, AI-driven sending volume, and master inbox for replies. Strong fit for outbound teams that want sending and warmup under one vendor. Plans start at $39/month for the Basic tier. See smartlead.ai.
Key features
Unlimited warmup on every plan
Unlimited mailbox rotation
Master inbox for centralized replies
Native CRM and Zapier integrations
Pros
- check_circleWarmup included at no extra cost
- check_circleOne vendor for sending and reputation
- check_circleFast-moving product roadmap
Cons
- cancelNo DMARC or blacklist monitoring
- cancelWarmup quality less curated than MailReach
- cancelOnly relevant if you do cold outreach
"Smartlead replaced MailReach plus Instantly. Unlimited warmup alone paid for the plan." Real user review placeholder, source: G2.
Suped
MODERN DMARC + BLACKLIST MONITORSuped is the lightweight modern alternative to Validity for DMARC reporting and blacklist monitoring. It parses aggregate XML reports into readable dashboards, surfaces unauthenticated senders, and runs continuous RBL checks. Pricing is friendly for SMBs (free tier includes 5K messages/month of DMARC processing). Good fit for marketing teams that need DMARC visibility without enterprise procurement. See suped.com.
Key features
DMARC aggregate report parsing and trend views
Continuous blacklist monitoring
BIMI and MTA-STS setup wizards
Free tier covers small domains
Pros
- check_circleModern UI built for marketers
- check_circleFree tier actually usable
- check_circleSelf-serve setup, no sales call
Cons
- cancelYounger product, fewer integrations
- cancelNo seedlist inbox placement testing
- cancelSmaller community than Validity
"Suped gave us DMARC visibility in a day. Validity quoted us a six-week implementation." Real user review placeholder, source: G2.
Validity Everest
ENTERPRISE DELIVERABILITY SUITEValidity (formerly 250ok and Return Path) sells Everest, the enterprise deliverability platform that combines seedlist inbox placement, sender reputation tracking, DMARC reporting, blacklist monitoring, and access to the Return Path Certified IP allowlist. Pricing is enterprise (quote-based, typically four-figure monthly) and onboarding includes a managed services component. Strong fit for marketing teams sending above 5M emails/month who need a single accountable vendor. See validity.com/everest.
Key features
Seedlist inbox placement across 100+ providers
Sender Score reputation tracking
DMARC, blacklist, and BIMI in one suite
Certified IP allowlist program access
Pros
- check_circleBroadest single-vendor coverage
- check_circleSender Score is an industry benchmark
- check_circleCertified IP allowlist boosts placement
Cons
- cancelEnterprise pricing, no transparent tier
- cancelLong onboarding with sales cycle
- cancelOverkill for SMB senders
"Everest is the only platform that gives our deliverability lead one screen for everything." Real user review placeholder, source: G2.
Category picks
Most deliverability programs run two or three of these tools at once. Here is who we would pair for each job.
Our pick: GlockApps
Largest seed network, expanded into DMARC and blacklist monitoring. Good single-vendor option.
Also strong: Mailmodo (free standalone test), Validity Everest (enterprise).
Our pick: Suped
Modern UI, generous free tier, self-serve setup. Pairs well with a separate sending ESP.
Also strong: Postmark DMARC Digests (free), Validity Everest (enterprise).
Our pick: MXToolbox
Free one-off checks plus paid continuous monitoring across 100+ RBLs. Industry default.
Also strong: Suped, GlockApps.
Our pick: MailReach
Dedicated warmup network with human-style replies and per-inbox reputation tracking.
Also strong: Smartlead (bundled with sending), Instantly (similar bundle).
Our pick: Mailsfinder deliverability checker
Free, instant audit of MX, SPF, DKIM, and DMARC with plain-language fix suggestions.
Also strong: MXToolbox SuperTool, Postmark DNS check.
Our pick: Postmark
Strict policy keeps shared IPs clean. Free DMARC Digests. Helpful support.
Also strong: Mailgun (Optimize add-on), MailerSend (free tier).
Pricing at a glance
Entry-level paid plans. Many tools have free tiers worth using before paying anything.
| Tool | Free tier | Entry paid plan | Best for |
|---|---|---|---|
| GlockApps | 1 test on signup | $59/mo | Seedlist testing |
| MailerSend | 3K emails/mo | $35/mo (50K) | SaaS transactional |
| Mailgun | 100/day trial | $35/mo (50K) | Developer-first scale |
| Mailmodo | Free seedlist test | $99/mo | AMP marketing email |
| MailReach | 7-day trial | $25/mo per inbox | Cold email warmup |
| Mailsfinder | 100 verifications/day, free DNS audit | From $39/mo | DNS audit + email lookup |
| MXToolbox | Free one-off checks | $129/mo monitoring | Blacklist + DNS |
| Postmark | 100 emails free + DMARC Digests free | $15/mo (10K) | Best transactional reputation |
| SendGrid | 100/day forever | $19.95/mo (50K) | High-volume scale |
| Smartlead | 14-day trial | $39/mo | Cold outreach with warmup |
| Suped | 5K DMARC msgs/mo | $25/mo | DMARC for SMBs |
| Validity Everest | No free tier | Enterprise quote | Enterprise deliverability |
Note: Most teams pair two or three tools. A common stack is Postmark or Mailgun for sending, Suped for DMARC, MXToolbox for blacklist, and the free Mailsfinder DNS audit for setup checks.
Frequently Asked Questions
What is an email deliverability tool?expand_more
What is the difference between a warmup tool and an inbox placement tool?expand_more
Do I need DMARC reporting if I already have SPF and DKIM set up?expand_more
Can I monitor blacklists for free?expand_more
Is Mailsfinder a deliverability tool?expand_more
What does inbox placement testing actually measure?expand_more
Should I use a transactional ESP like Postmark or Mailgun for cold outreach?expand_more
What is the cheapest way to start fixing deliverability?expand_more
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About the author
Harsh Shah
Founder, Mailsfinder
Harsh founded Mailsfinder after running outbound for hundreds of B2B teams and watching the same gap repeat: tools that generate sends but not replies, SEO that generates traffic but not pipeline. He currently consults for ClickUp and three other B2B SaaS companies on pipeline-driven SEO and outbound, and previously led growth at Databox and Darwinbox. Across 50+ B2B SaaS engagements he scaled one platform from $2K to $50K MRR through organic search, drove 35% traffic lifts via content audits, and launched comparison pages with 22% conversion lift.
Expertise: Pipeline-driven SEO and AEO, first-principles outbound, B2B SaaS growth consulting, email deliverability, comparison and alternative page SEO
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