# Email deliverability and testing tools for small business buyers: what AI models recommend, November 2026

Gane Index, November 2026 Edition. Asked as "email deliverability tool" and as "inbox placement and email testing platform", six framings each, to fourteen models with search on, on behalf of a small B2B company. Added to the November 2026 Edition. Page: https://www.gane.ai/index/gtm/marketing/email-deliverability-and-testing/2026-11/smb

**Standing:** GlockApps leads with 25% of first choices; verdict contested. 56 first choices across the direct, paraphrase, budget and scale prompts.

## First-choice share

| Rank | Product | Share | Negative rate | Labels |
|---|---|---|---|---|
| 1 | [GlockApps](https://www.gane.ai/index/gtm/vendors/glockapps/index.md) | 25% | 6% | 54 |
| 2 | [Sender](https://www.gane.ai/index/gtm/vendors/sender/index.md) | 12% | 0% | 10 |
| 3 | [Instantly](https://www.gane.ai/index/gtm/vendors/instantly/index.md) | 11% | 0% | 15 |
| 4 | [Mail-Tester](https://www.gane.ai/index/gtm/vendors/mail-tester/index.md) | 7% | 6% | 35 |
| 5 | [Google Postmaster Tools](https://www.gane.ai/index/gtm/vendors/google-postmaster-tools/index.md) | 5% | 0% | 36 |
| 6 | [MXToolbox](https://www.gane.ai/index/gtm/vendors/mxtoolbox/index.md) | 5% | 3% | 37 |
| 7 | [MailerLite](https://www.gane.ai/index/gtm/vendors/mailerlite/index.md) | 5% | 0% | 11 |
| 8 | [MailReach](https://www.gane.ai/index/gtm/vendors/mailreach/index.md) | 4% | 5% | 21 |
| 9 | [Brevo](https://www.gane.ai/index/gtm/vendors/brevo/index.md) | 4% | 0% | 13 |
| 10 | [Unspam.email](https://www.gane.ai/index/gtm/vendors/unspam-email/index.md) | 2% | 0% | 11 |
| 21 | [Litmus](https://www.gane.ai/index/gtm/vendors/litmus/index.md) | 2% | 59% | 22 |
| 22 | [ZeroBounce](https://www.gane.ai/index/gtm/vendors/zerobounce/index.md) | 0% | 5% | 22 |

Rank is by share of first choices among all 107 products named; products with the same share are tied, and the order among them carries no meaning. The table lists those with at least 10 labels.

## Each model's first choice on the direct prompt

- Claude Haiku 4.5: no first choice
- GPT-5.4 mini: Instantly; alternatives Bouncer, Brevo
- Gemini 3.5 Flash: Instantly, Smartlead; alternatives EasyDMARC, GlockApps, MailReach
- Perplexity Sonar: MailerCheck; alternatives EasyDMARC, GlockApps, Google Postmaster Tools, MXToolbox
- Grok 4.20: GlockApps; alternatives Brevo, Instantly, MXToolbox, MailReach
- Mistral Small: GlockApps, MailerLite; alternatives Instantly
- DeepSeek V4 Flash: Instantly; alternatives GlockApps, MailReach, ZeroBounce
- Llama 4 Maverick: Sender
- Qwen 3.7 Flash: Instantly, Lemlist; alternatives EasyDMARC, GlockApps, MailReach, Sender
- Kimi K2: MailReach; alternatives GlockApps, MXToolbox, ZeroBounce
- GLM 4.7 FlashX: GlockApps; alternatives MailReach
- MiniMax M2.5: Instantly; alternatives Google Postmaster Tool, MXToolbox
- GPT-6 Luna: GlockApps; alternatives Google Postmaster Tools, MailReach
- Muse Glimmer 30B: Sender; alternatives GlockApps, Google Postmaster Tools, MXToolbox, Mail-Tester

## Sources the answers cite

73 of 84 answers came back with a source list, from 14 of 14 models. Sites named in the most answers:

- g2.com: 29 answers, 40 citations
- toolradar.com: 27 answers, 32 citations
- unspam.email: 25 answers, 32 citations
- prospeo.io: 21 answers, 25 citations
- myemailverifier.com: 21 answers, 21 citations
- glockapps.com: 19 answers, 27 citations
- emailtooltester.com: 19 answers, 22 citations
- softwaresuggest.com: 17 answers, 17 citations

Pages named in the most answers:

- https://toolradar.com/best/email-deliverability/for/small-businesses (26 answers)
- https://myemailverifier.com/blog/email-deliverability-tools (21 answers)
- https://unspam.email/articles/email-deliverability-softwares (16 answers)
- https://wiredmessenger.com/blogs/best-email-deliverability-tools (13 answers)
- https://softwaresuggest.com/email-deliverability-tools (12 answers)
- https://g2.com/categories/email-deliverability/small-business (10 answers)
- https://saleshandy.com/blog/email-deliverability-tools (10 answers)
- https://trustradius.com/categories/email-deliverability?company-size (10 answers)
- https://emailtooltester.com/en/email-deliverability-test (9 answers)
- https://mailgun.com/blog/deliverability/email-deliverability-tools (9 answers)

## Warned against

- Litmus: 13 of 22 labels negative. "Don't Buy: High-End Testing Suites (Too Soon) Tools like Litmus or Pardot ... for a small business, buying them early is a waste of capital." (Qwen 3.7 Flash, negative prompt)
- Email on Acid: 4 of 14 labels negative. "Neither Litmus nor Email on Acid can tell you if your email avoids spam filters, lands in the primary inbox" (Claude Haiku 4.5, negative prompt)
- Everest: 4 of 5 labels negative. "Tools like GlockApps, Everest, and others rely on seed lists... paying for these when you could test directly to your own Gmail/Outlook accounts may be wasteful." (DeepSeek V4 Flash, negative prompt)
- Validity Everest: 5 of 8 labels negative. "High-Cost Enterprise Suites (Overkill / Financial Trap)
* Examples: *Validity Everest (formerly Return Path / 250ok)*" (Gemini 3.5 Flash, negative prompt)

## Movement since October 2026

Floor: 11 points of share, measured on the calibration repeat.
Same leader: GlockApps at 25%.

- Sender: 2% to 12%, +10. Cleared the floor by -1 points · rank 16 → 2 of 107.
- Instantly: 5% to 11%, +6. Inside the floor by 5 points · rank 7 → 3 of 107.
- Google Postmaster Tools: 10% to 5%, −5. Inside the floor by 6 points · rank 2 → 5 of 107.
- ZeroBounce: 5% to 0%, −5. Inside the floor by 6 points · rank 5 → 22 of 107.
- MailerLite: 2% to 5%, +3. Inside the floor by 8 points · rank 21 → 7 of 107.
- Litmus: 5% to 2%, −3. Inside the floor by 8 points · rank 8 → 21 of 107.
- Microsoft SNDS: 3% to 0%, −3. Inside the floor by 8 points · rank 9 → 24 of 107.
- Brevo: 2% to 4%, +2. Inside the floor by 9 points · rank 14 → 9 of 107.
- Unspam.email: 0% to 2%, +2. Inside the floor by 9 points · rank 32 → 10 of 107.
- Mailtrap Email Sandbox: 2% to 0%, −2. Inside the floor by 9 points · rank 11 → 23 of 107.
- Folderly: 2% to 0%, −2. Inside the floor by 9 points · rank 19 → 28 of 107.
- Warmbox: 2% to 0%, −2. Inside the floor by 9 points · rank 12 → 42 of 107.

## Record

- Method: https://www.gane.ai/index/gtm/methodology
- License: CC BY 4.0. Cite as Gane Index, November 2026 Edition, www.gane.ai/index/gtm.