Google Postmaster Tools vs Mail-Tester
Zero of fourteen models named Google Postmaster Tools first on the direct prompt; zero named Mail-Tester. Google Postmaster Tools was named by thirteen of the fourteen models and Mail-Tester by eleven and Google Postmaster Tools carries 30 labels and Mail-Tester 20, so the shares are not directly comparable.
Google Postmaster Tools
accepted challengerBy Google, Mountain View, California, United States, founded 1998. Named in one category this edition.
Named in one category this edition.
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; every quote names the model and the prompt it came from. Both figures come from the email deliverability and testing tools page.
By framing
Across every category in the October 2026 Edition, Google Postmaster Tools and Mail-Tester were named in the same answer thirty times, of the 77 answers naming Google Postmaster Tools and the 52 naming Mail-Tester. In those answers Mail-Tester took the first choice two times and Google Postmaster Tools seven.
Every model, every framing
| Model | DirectGP | ParaphraseGP | ComparativeGP | Budget-constrainedGP | Scale-constrainedGP | NegativeGP |
|---|---|---|---|---|---|---|
| Claude Haiku 4.5 | | |||||
| GPT-5.4 mini | ||||||
| Gemini 3.5 Flash | | GP | GP | |||
| Perplexity Sonar | GP | |||||
| Grok 4.1 Fast | GP | | GP | GP | ||
| Mistral Small | GP | GP | ||||
| DeepSeek V4 Flash | GP | GP | GP | GP | GP | |
| Llama 4 Maverick | GP | |||||
| Qwen 3.7 Flash | GP | GP | ||||
| Kimi K2 | | GP | GP | |||
| GLM 4.7 FlashX | GP | | ||||
| MiniMax M2.5 | | GP | ||||
| GPT-6 Luna | GP | |||||
| Muse Glimmer 30B | GP | | |
Mail-TesterGP first choiceGP named as an alternativeGP argued againstblank: not namedEach cell is one answer, Google Postmaster Tools on the left and Mail-Tester on the right.The direct prompt
Neither was the first choice, one was named
1 of 14 modelsThe answer put something else first and named one of the two as an alternative.Neither was named
13 of 14 modelsThe answer made no first choice from these two in this category.Bold names in an answer are the products the judge labeled a first choice; a model naming several gives each of them that label. The full answer text for every row is in the record.
By buyer segment
Mail-Tester5%#5 of 15Mail-Tester5%#5 of 12Mail-Tester0%#– of 14What the models said about Google Postmaster Tools
Every negative label with a quote, up to three, then the highest-weighted positives, up to three. Three of four in this category shown.
“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 Mail-Tester
Every negative label with a quote, up to three, then the highest-weighted positives, up to three. Six of eight in this category shown.
“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
Comparisons are drawn for the top eight products in each category, each against each. The output is the models' output; nothing here is a recommendation by the index.