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Email security · November 2026 Edition
Microsoft Defender for Office 365 vs Mimecast Email Security
Six of fourteen models named Microsoft Defender for Office 365 first on the direct prompt; three named Mimecast Email Security. Both were named by all fourteen models and Microsoft Defender for Office 365 carries 63 labels and Mimecast Email Security 54, so the shares are not directly comparable.
Named in three categories this edition.
Named in one category this edition.
First-choice share45%8%Of first choices across the direct, paraphrase, budget and scale prompts, 0 to 100.
Negative rate3%19%Negative labels as a share of the product's labels, 0 to 100.
Rank in category#1#3A position in a field of 9; printed, not drawn.
Labels6354A count; the two differ.
The two percentage rows are drawn on one 0 to 100 track, Microsoft Defender for Office 365 reading right to left. Rank and label count are printed, not drawn.Abnormal AI was named alongside these two in ten of the fourteen direct answers. Microsoft Defender for Office 365 vs Abnormal AI · Microsoft Defender for Office 365 vs Check Point Harmony Email & Collaboration · Microsoft Defender for Office 365 vs IRONSCALES
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 security page.
By framing
How many of the fourteen models made each the first choice, per way of asking, and how many argued against it.
Microsoft Defender for Office 365First choices, of fourteen modelsMimecast Email Security
Direct631 against Mimecast Email Security
Paraphrase911 against Mimecast Email Security
Comparative50
Budget-constrained702 against Mimecast Email Security
Scale-constrained201 against Microsoft Defender for Office 365 · 1 against Mimecast Email Security
Negative111 against Microsoft Defender for Office 365 · 5 against Mimecast Email Security
Bars are first choices, 0 to 14 each sideModels that argued againstA model can name both, so the two sides of a row do not sum to fourteen.
Across every category in the November 2026 Edition, Microsoft Defender for Office 365 and Mimecast Email Security were named in the same answer 127 times, of the 193 answers naming Microsoft Defender for Office 365 and the 154 naming Mimecast Email Security. In those answers Mimecast Email Security took the first choice seven times and Microsoft Defender for Office 365 fifty-five.
Every model, every framing
The eighty-four answers behind the chart above, one cell each: where Microsoft Defender for Office 365 and Mimecast Email Security stood in it.
| 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 | | | | |
Microsoft Defender for Office 365 Mimecast Email Security first choice named as an alternative argued againstblank: not namedEach cell is one answer, Microsoft Defender for Office 365 on the left and Mimecast Email Security on the right.The direct prompt
The plain question, one answer per model, grouped by where Microsoft Defender for Office 365 and Mimecast Email Security stood in it.
Both were the first choice
1 of 14 modelsThe answer named them together, and the judge labeled each a first choice.GPT-5.4 miniMicrosoft Defender for Office 365, Mimecast Email Security alternatives: Barracuda Email Protection, IRONSCALES, Proofpoint Email Protection
Microsoft Defender for Office 365 first, Mimecast Email Security an alternative
5 of 14 modelsMimecast Email Security was named in the answer but not as the choice, or not at all.Perplexity SonarMicrosoft Defender for Office 365 alternatives: Abnormal AI, Barracuda Email Protection, Check Point Harmony Email & Collaboration
Grok 4.20Microsoft Defender for Office 365 alternatives: Abnormal AI, Mimecast Email Security, Proofpoint Email Protection
Mistral SmallMicrosoft Defender for Office 365 alternatives: Barracuda Email Protection, Check Point Harmony Email & Collaboration
DeepSeek V4 FlashAbnormal AI, Microsoft Defender for Office 365 alternatives: Hornetsecurity 365 Total Protection, Mimecast Email Security
Llama 4 MaverickMicrosoft Defender for Office 365 alternatives: Barracuda Email Protection, ContentCatcher, SpamTitan
Mimecast Email Security first, Microsoft Defender for Office 365 an alternative
2 of 14 modelsMicrosoft Defender for Office 365 was named in the answer but not as the choice, or not at all.Kimi K2Mimecast Email Security alternatives: Abnormal AI, Barracuda Email Protection, IRONSCALES, Microsoft Defender for Office 365, Proofpoint Email Protection
GLM 4.7 FlashXMimecast Email Security alternatives: Abnormal AI, Barracuda Email Protection, Microsoft Defender XDR, Proofpoint Email Protection
Neither was the first choice, one was named
5 of 14 modelsThe answer put something else first and named one of the two as an alternative.Gemini 3.5 FlashAbnormal AI, Check Point Harmony Email & Collaboration alternatives: Microsoft Defender for Office 365, Mimecast Email Security, Proofpoint Email Protection
Qwen 3.7 FlashProofpoint Email Protection alternatives: Abnormal AI, Check Point Harmony Email & Collaboration, IRONSCALES, Mimecast Email Security
MiniMax M2.5Check Point Harmony Email & Collaboration, IRONSCALES alternatives: Abnormal AI, Mimecast Email Security, Proofpoint Email Protection
GPT-6 LunaAbnormal AI alternatives: Check Point Harmony Email & Collaboration, Microsoft Defender for Office 365
Muse Glimmer 30BIRONSCALES alternatives: Abnormal AI, Barracuda Email Protection, Microsoft Defender for Office 365, Mimecast Email Security, Proofpoint Email Protection
Neither was named
1 of 14 modelsThe answer made no first choice from these two in this category.Claude Haiku 4.5no first choice
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
The same question asked on behalf of a different buyer. Each standing is computed within its segment and they are never added together. The figures above are the mid-market standing, which is the one the category orders by.
Small business
Microsoft Defender for Office 365 leads by forty-three points.
Microsoft Defender for Office 36543%#1 of 10Mimecast Email Security0%#10 of 10Mid-marketThe figures above
Microsoft Defender for Office 365 leads by thirty-eight points.
Microsoft Defender for Office 36545%#1 of 9Mimecast Email Security8%#3 of 9Enterprise
Microsoft Defender for Office 365 leads by seventeen points.
Microsoft Defender for Office 36524%#2 of 10Mimecast Email Security7%#4 of 10What the models said about Microsoft Defender for Office 365
Every negative label with a quote, up to three, then the highest-weighted positives, up to three. Five of six in this category shown.
“Microsoft 365 users experience 3x more email-related incidents than Google Workspace users” Grok 4.20 · negative prompt · soft negative
“Good value, but many orgs find native M365 needs supplementing.” DeepSeek V4 Flash · scale prompt · soft negative
“Integrated cloud-native solutions: Microsoft Defender for Office 365, Google Workspace security (native integration, no MX changes)” Kimi K2 · negative prompt · first choice
“Best for Microsoft 365 Users: Microsoft Defender for Office 365 (Plan 1) ... often the cheapest path to enterprise-grade features” Gemini 3.5 Flash · budget prompt · first choice
“If I had to pick one default answer: Microsoft Defender for Office 365 if you're Microsoft-centric and want the least friction.” GPT-5.4 mini · direct prompt · first choice
What the models said about Mimecast Email Security
Every negative label with a quote, up to three, then the highest-weighted positives, up to three. Six of eight in this category shown.
“Mimecast — typically priced for mid-market and enterprise” DeepSeek V4 Flash · budget prompt · hard negative
“Choose Mimecast or Proofpoint only if archiving, continuity, DLP, or regulated-industry controls justify the additional platform complexity.” Perplexity Sonar · direct prompt · soft negative
“Unlike legacy Secure Email Gateways (SEGs) like Mimecast or Proofpoint Enterprise, ICES solutions deploy via cloud APIs in minutes” Gemini 3.5 Flash · paraphrase prompt · soft negative
“Mimecast if you want a more dedicated email-security layer with broader controls and stronger operational features.” GPT-5.4 mini · direct prompt · first choice
“Top Pick: Mimecast Advanced Email Security ... arguably the best all-around fit for mid-sized B2B companies” DeepSeek V4 Flash · paraphrase prompt · first choice
“Best All-in-One Platform: Mimecast ... rated as best for mid-market and enterprise organizations” Kimi K2 · direct prompt · first choice
Also compared
Microsoft Defender for Office 365 vs Abnormal AIMicrosoft Defender for Office 365 vs Check Point Harmony Email & CollaborationMicrosoft Defender for Office 365 vs IRONSCALESMicrosoft Defender for Office 365 vs Proofpoint Email ProtectionMicrosoft Defender for Office 365 vs Barracuda Email ProtectionAbnormal AI vs Mimecast Email SecurityMimecast Email Security vs Check Point Harmony Email & CollaborationMimecast Email Security vs IRONSCALESMimecast Email Security vs Proofpoint Email ProtectionMimecast Email Security vs Barracuda Email ProtectionAll twenty-one head-to-head pages and the full email security standing
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.