# GlockApps vs MXToolbox: which do AI models recommend for email deliverability, October 2026

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

| | First-choice share | Rank | Negative rate | Labels | Models naming it |
|---|---|---|---|---|---|
| GlockApps | 34% | #1 of 12 | 7% | 57 | 14 of 14 |
| MXToolbox | 5% | #4 of 12 | 10% | 31 | 12 of 14 |

## The direct prompt, model by model

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

## What the models said about GlockApps

- "GlockApps became popular for one specific capability... Test credits do not roll over... stops at telling you what is wrong." (Muse Glimmer 30B, negative prompt, soft negative)
- "a fraction of what enterprise tools like GlockApps ($85+/month) or ZeroBounce ($99/month) would cost" (DeepSeek V4 Flash, budget prompt, soft negative)
- "Good for deeper testing, but pricier; consider only if you have repeated deliverability issues" (GLM 4.7 FlashX, budget prompt, soft negative)
- "For most mid-sized B2B companies, GlockApps offers the best balance of comprehensive diagnostics, B2B-appropriate seed lists, and reasonable pricing." (Claude Haiku 4.5, paraphrase prompt, first choice)
- "the best choice is usually GlockApps if you want the strongest balance of inbox placement testing, DMARC monitoring, and mid-market pricing" (Perplexity Sonar, direct prompt, first choice)
- "For most mid-sized B2B companies, GlockApps is the best choice due to its depth of inbox placement testing and deliverability diagnostics." (Mistral Small, paraphrase 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.