# Google Postmaster Tools vs MXToolbox: which do AI models recommend for email deliverability, October 2026

GTM AI Recommendation Index, October 2026 Edition, Email deliverability and testing tools. Zero of fourteen models named Google Postmaster Tools first on the direct prompt; zero named MXToolbox. Page: https://gtm-ai-index.com/marketing/email-deliverability-and-testing/google-postmaster-tools-vs-mxtoolbox/

| | First-choice share | Rank | Negative rate | Labels | Models naming it |
|---|---|---|---|---|---|
| Google Postmaster Tools | 9% | #2 of 12 | 0% | 30 | 13 of 14 |
| MXToolbox | 5% | #4 of 12 | 10% | 31 | 12 of 14 |

## The direct prompt, model by model

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

## What the models said about Google Postmaster Tools

- "Set up Google Postmaster Tools (free) and Microsoft SNDS (free). These are the only tools that provide direct, unvarnished reputation data" (Gemini 3.5 Flash, negative prompt, first choice)
- "Best free option: Stack Google Postmaster Tools, Microsoft SNDS, Yahoo Sender Hub, MXToolbox, Mail Tester, AboutMyEmail, and Sender Hub." (GLM 4.7 FlashX, budget prompt, first choice)
- "Best overall for near-zero budget: free monitoring stack with Google Postmaster Tools, Microsoft SNDS, MXToolbox, and Yahoo Sender Hub." (Perplexity Sonar, budget prompt, first choice)

## What the models said about MXToolbox

- "MxToolbox is an infrastructure diagnostic tool, not a campaign email testing tool... best used only for specific DNS and infrastructure checks, not comprehensive campaign testing." (Claude Haiku 4.5, negative prompt, hard negative)
- "Free tools like Mail Tester and MxToolbox handle basic checks but lack the depth for production workflows." (Muse Glimmer 30B, negative prompt, soft negative)
- "lack depth for production-scale testing, inbox placement simulation, or ongoing monitoring" (Grok 4.1 Fast, negative prompt, soft negative)
- "Best free option: Stack Google Postmaster Tools, Microsoft SNDS, Yahoo Sender Hub, MXToolbox, Mail Tester, AboutMyEmail, and Sender Hub." (GLM 4.7 FlashX, budget prompt, first choice)
- "free monitoring stack with Google Postmaster Tools, Microsoft SNDS, MXToolbox, and Yahoo Sender Hub" (Perplexity Sonar, 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.