Litmus vs Mail-Tester
One of fourteen models named Litmus first on the direct prompt; zero named Mail-Tester. Litmus was named by fourteen of the fourteen models and Mail-Tester by eleven and Litmus carries 21 labels and Mail-Tester 27, so the shares are not directly comparable.
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
LitmusFirst choices, of fourteen modelsMail-Tester
Across every category in the November 2026 Edition, Litmus and Mail-Tester were named in the same answer twenty-nine times, of the 68 answers naming Litmus and the 70 naming Mail-Tester. In those answers Mail-Tester took the first choice one time and Litmus one.
Every model, every framing
| Model | Direct | Paraphrase | Comparative | Budget-constrained | Scale-constrained | Negative |
|---|---|---|---|---|---|---|
| Claude Haiku 4.5 | | | ||||
| GPT-5.4 mini | | | | |||
| Gemini 3.5 Flash | | | | | ||
| Perplexity Sonar | | | | |||
| Grok 4.20 | | | ||||
| Mistral Small | | | | |||
| DeepSeek V4 Flash | | | | | ||
| Llama 4 Maverick | ||||||
| Qwen 3.7 Flash | | | ||||
| Kimi K2 | | | | |||
| GLM 4.7 FlashX | | |||||
| MiniMax M2.5 | | | ||||
| GPT-6 Luna | | |||||
| Muse Glimmer 30B | | | | |
Litmus Mail-Tester first choice named as an alternative argued againstblank: not namedEach cell is one answer, Litmus on the left and Mail-Tester on the right.The direct prompt
Litmus first, Mail-Tester not the choice
1 of 14 modelsMail-Tester was named in the answer but not as the choice, or not at all.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
12 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-Tester7%#4 of 15Litmus2%#11 of 15Litmus6%#3 of 19Mail-Tester2%#8 of 19What the models said about Litmus
Every negative label with a quote, up to three, then the highest-weighted positives, up to three. Five of six in this category shown.
“Caveat: These are primarily design/rendering testing tools. Their inbox placement features are secondary.” Kimi K2 · paraphrase prompt · soft negative
“Overkill (and pricey) for mid-sized teams; better for enterprises” DeepSeek V4 Flash · paraphrase prompt · soft negative
“I'd generally recommend Litmus if your priority is email testing, QA, rendering previews, and team workflow” GPT-5.4 mini · paraphrase prompt · first choice
“Best Overall for Marketing Workflow & Outlook Testing: Litmus” Gemini 3.5 Flash · paraphrase prompt · first choice
“Marketing team sending campaigns: Litmus + GlockApps” GPT-5.4 mini · comparative 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 does one thing well: it runs your email through SpamAssassin and checks your SPF, DKIM, and DMARC records. That's useful. It's also not enough.” Muse Glimmer 30B · negative prompt · soft negative
“Email "spam score" checkers such as Mail-Tester: good for finding technical problems, but a favorable score does not predict inbox placement.” Perplexity Sonar · negative prompt · soft negative
“Use these only as a diagnostic aid, not as a primary decision-making tool.” DeepSeek V4 Flash · negative prompt · soft negative
“Start with Unspam's free tier or Mail-Tester if you need immediate, low-cost testing.” Kimi K2 · budget prompt · first choice
“Instant spam score (0–10) based on content, authentication, and reputation. No signup needed for basic use.” Grok 4.20 · comparative prompt · alternative
“Cited as a best deliverability testing tool in 2026 with a free spam score, real inbox-placement testing” Muse Glimmer 30B · comparative prompt · alternative
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.