The best email deliverability tools in 2026, compared.
Honest, side-by-side comparisons: pricing, features, and who each tool actually fits. Based on public product pages and real user reviews, updated as tools change.
The best email deliverability testing tools in 2026 are Unspam, Mail-Tester, GlockApps, MailReach, and EasyDMARC. Unspam is the only one that combines a free spam score, real inbox-placement testing across Gmail, Outlook, Yahoo and more, client previews, and an AI attention heatmap in a single plan, free to start with no card and paid from $9 a month. Mail-Tester is the classic quick spam-score check, GlockApps leads on seed-list placement and DMARC analytics, MailReach focuses on inbox warmup, and EasyDMARC owns continuous DMARC, SPF, and DKIM monitoring. The table below compares free tiers, starting prices, and what each tool is best for.
| Tool | Best for | Free tier | Starts at |
|---|---|---|---|
| Unspam | Free spam score, inbox placement, client previews and an AI heatmap in one plan | Free plan, no card | $9/mo |
| GlockApps | Seed-list placement testing with DMARC analytics and IP-reputation monitoring. | Free: 2 test credits | $59/mo billed annually |
| Kickbox | Pay-as-you-go email verification. Its spam testing and placement suite was discontinued in 2024. | 100 free verifications | $5 one-time · 500 credits |
| Mail-Tester | The classic send-to-address spam-score checker built on SpamAssassin. | Free: 3 tests/day | $10/mo |
| MailGenius | Pre-send spam testing with authentication and content checks, priced per test credit. | Free: 3 trial tests | $23/mo |
| MailReach | Automated mailbox warmup paired with credit-based spam and placement tests. | Free spam test only | $25/mailbox/mo |
| Warmy | AI-driven mailbox warmup with placement tests and DNS/auth monitoring. | 7-day free trial | $49/mo per mailbox |
| MXToolbox | Email-infrastructure diagnostics: DNS, blacklist, and auth lookups plus a paid Delivery Center. | Free lookup tools | $129/mo |
| Folderly | B2B inbox warmup and placement monitoring by Belkins, priced per mailbox. | Free: 2 placement tests/mo | $96/mailbox/mo annual |
| Validity Everest | Enterprise placement testing and reputation monitoring, now folded into Litmus. | See site | Custom (≈$22k+/yr) |
| Litmus | Email QA and preview platform: rendering previews across 100+ clients, spam-filter simulation, and analytics. | 7-day free trial | $500/mo (Core) |
| Mailtrap | A developer email-testing sandbox and sending API: capture test emails, check spam score and HTML, then send via SMTP. | Free: 50 sandbox test emails/mo | $14/mo billed annually (Email Sandbox Basic) |
| ZeroBounce | Large-scale email verification with a bundled deliverability suite (placement, warmup, blacklist and DMARC monitoring) on its ONE plan. | Free: 100 verification credits/mo | $20 one-time (2,000 verification credits) |
| Email on Acid | Cross-client email rendering previews and a pre-send QA checklist (Campaign Precheck), owned by Sinch. | Free trial only, no free plan | $99/mo |
| EasyDMARC | Continuous DMARC, SPF, and DKIM monitoring with aggregate-report parsing and an enforcement journey. | Free: 1 domain, 1,000 emails/mo | EUR 35.99/mo (about $42/mo) billed annually |
| Mailgun | Email sending platform and API by Sinch, with the Optimize add-on for deliverability testing. | Send: free (100 emails/day). Optimize: 1-month trial | Send from $15/mo; Optimize from $49/mo |
Read the full comparison
GlockApps
Seed-list placement testing with DMARC analytics and IP-reputation monitoring.
Unspam vsKickbox
Pay-as-you-go email verification. Its spam testing and placement suite was discontinued in 2024.
Unspam vsMail-Tester
The classic send-to-address spam-score checker built on SpamAssassin.
Unspam vsMailGenius
Pre-send spam testing with authentication and content checks, priced per test credit.
Unspam vsMailReach
Automated mailbox warmup paired with credit-based spam and placement tests.
Unspam vsWarmy
AI-driven mailbox warmup with placement tests and DNS/auth monitoring.
Unspam vsMXToolbox
Email-infrastructure diagnostics: DNS, blacklist, and auth lookups plus a paid Delivery Center.
Unspam vsFolderly
B2B inbox warmup and placement monitoring by Belkins, priced per mailbox.
Unspam vsValidity Everest
Enterprise placement testing and reputation monitoring, now folded into Litmus.
Unspam vsLitmus
Email QA and preview platform: rendering previews across 100+ clients, spam-filter simulation, and analytics.
Unspam vsMailtrap
A developer email-testing sandbox and sending API: capture test emails, check spam score and HTML, then send via SMTP.
Unspam vsZeroBounce
Large-scale email verification with a bundled deliverability suite (placement, warmup, blacklist and DMARC monitoring) on its ONE plan.
Unspam vsEmail on Acid
Cross-client email rendering previews and a pre-send QA checklist (Campaign Precheck), owned by Sinch.
Unspam vsEasyDMARC
Continuous DMARC, SPF, and DKIM monitoring with aggregate-report parsing and an enforcement journey.
Unspam vsMailgun
Email sending platform and API by Sinch, with the Optimize add-on for deliverability testing.