# MailReach vs Mail-Tester: which do AI models recommend for email deliverability, October 2026

GTM AI Recommendation Index, October 2026 Edition, Email deliverability and testing tools. Two of fourteen models named MailReach first on the direct prompt; zero named Mail-Tester. Page: https://gtm-ai-index.com/marketing/email-deliverability-and-testing/mailreach-vs-mail-tester/

| | First-choice share | Rank | Negative rate | Labels | Models naming it |
|---|---|---|---|---|---|
| MailReach | 7% | #3 of 12 | 7% | 30 | 11 of 14 |
| Mail-Tester | 5% | #5 of 12 | 25% | 20 | 11 of 14 |

## The direct prompt, model by model

- DeepSeek V4 Flash: mailreach first (first choices: MailReach) (alternatives: GlockApps, Google Postmaster Tools, MXToolbox)
- GLM 4.7 FlashX: mailreach first (first choices: GlockApps, MailReach) (alternatives: Folderly, Warmy)
- Perplexity Sonar: neither first, one named (first choices: GlockApps) (alternatives: Amplemarket, MailReach, NeverBounce)
- Grok 4.1 Fast: neither first, one named (first choices: GlockApps) (alternatives: MailReach, Validity Everest, Warmy.io)
- Mistral Small: neither first, one named (first choices: Folderly, GlockApps) (alternatives: MailReach, Zoho CRM)
- Kimi K2: neither first, one named (first choices: GlockApps, Instantly) (alternatives: HubSpot Sales Hub, MailReach)
- Muse Glimmer 30B: neither first, one named (first choices: GlockApps) (alternatives: MailReach, Validity Everest)
- Claude Haiku 4.5: neither named (first choices: InboxArmy, MailBrace) (alternatives: Folderly, GlockApps, HubSpot, Mailsoftly)
- GPT-5.4 mini: neither named (first choices: Mailgun Optimize) (alternatives: GlockApps)
- Gemini 3.5 Flash: neither named (first choices: Allegrow, GlockApps) (alternatives: Mailgun Optimize, ZeroBounce)
- Llama 4 Maverick: neither named (first choices: GlockApps)
- Qwen 3.7 Flash: neither named (first choices: GlockApps) (alternatives: 250ok, Instantly, Kickbox, Lemlist, Valimail, ZeroBounce)
- MiniMax M2.5: neither named (first choices: Folderly, Mailtrap) (alternatives: EasyDMARC, MXToolbox)
- GPT-6 Luna: neither named (first choices: Validity Everest) (alternatives: GlockApps)

## What the models said about MailReach

- "The tool may not accurately reflect deliverability for all B2B scenarios, so approach with caution if your audience is large or uses corporate email systems." (Mistral Small, negative prompt, soft negative)
- "Tools like GlockApps, MailReach, and Mailtrap vary in real-time validation depth — only some verify addresses at scale before sending." (Muse Glimmer 30B, negative prompt, soft negative)
- "MailReach is the best budget option for warmup and placement testing bundled into one affordable plan" (Claude Haiku 4.5, budget prompt, first choice)
- "or MailReach (warm‑up + testing at a lower price)" (GLM 4.7 FlashX, direct prompt, first choice)
- "MailReach is the best overall choice in 2026" (DeepSeek V4 Flash, direct prompt, first choice)

## What the models said about Mail-Tester

- "Mail-Tester scores against a single seed address, so it can't tell you where your email lands across a multi-ISP seed network" (Claude Haiku 4.5, negative prompt, hard negative)
- "These are inaccurate and misleading... do not base business decisions on them." (DeepSeek V4 Flash, negative prompt, hard negative)
- "Avoid: Relying solely on these web-based scores. They are useful for a quick syntax check but should not be your primary deliverability testing tool." (GLM 4.7 FlashX, negative prompt, soft negative)
- "Mail-Tester for occasional pre-send checks of a message and its sending setup. It allows up to 3 free tests per day." (GPT-6 Luna, budget prompt, first choice)
- "The best email deliverability tool for a company with a limited budget is Mail-Tester or Unspam for pre-send testing" (Llama 4 Maverick, budget prompt, first choice)
- "Start with free tools → Google Postmaster Tools + MXToolbox + Mail-Tester free tier" (Kimi K2, budget prompt, first choice)

Share is the count of first choices across the direct, paraphrase, budget and scale prompts over all fourteen models, for a mid-market B2B company; rank is within the category. Comparisons are drawn for the top eight products in each category. Published under CC BY 4.0; the output is the models' output, and nothing here is a recommendation by the index.