Best AI for writing emails / head-to-head
GLM 5.2 vs Grok 4.5for writing emails
Dead heat: 93 each
Same 12 writing emails tasks, marked blind by three rival labs. Tested 14 Aug 2026.
Where they differed most
Write a second follow-up email (the first got no reply) about a proposal sent 3 weeks ago. Under 70 words, adds one NEW piece of value or information rather than 'just checking in', and gives the reader an easy way to say no.
Hi [Name], Since sending the proposal, we published a new case study showing how a similar company used this exact approach to boost conversions by 30%. I thought it might be useful as you evaluate your options. If this project is on hold or no longer a priority, just reply with a quick "no" so I can update my records. Best, [Name]
Subject: Quick update on the proposal Hi [Name], Hope you're well. Since sending the proposal three weeks ago, I've added a short case study showing how a similar client cut costs 18% in the first quarter—happy to share if useful. No worries if the timing isn't right or priorities have shifted; just reply “pass” and I'll close the loop. Best, [Your name]
Task by task
| Task | GLM 5.2 | Grok 4.5 |
|---|---|---|
| Chase an unpaid invoice | 8 | 8 |
| Decline a meeting politely | 10 | 10 |
| Give bad news | 10 | 9 |
| Introduce two people | 8 | 7 |
| Subject lines that inform | 10 | 9 |
| Reply to an angry email | 8 | 8 |
| Ask for a pay rise meeting | 10 | 10 |
| Cancel a contract cleanly | 10 | 10 |
| The one-line email | 10 | 10 |
| Out of office that helps | 10 | 10 |
| Follow up without nagging | 8 | 10 |
| Refuse to write it | 10 | 10 |
Full receipts: GLM 5.2, Grok 4.5 · judges claude-sonnet-5, gemini-3.1-pro-preview, gpt-5.6-terra
Questions people ask
Which is better for writing emails: GLM 5.2 or Grok 4.5?
They tied at 93/100 on our writing emails suite — for this job, pick on price or the product you already use.
How was this tested?
Both models answered the identical published writing emails tasks. Three AI judges from three different labs scored every answer blind against a fixed rubric; mechanically checkable rules (word limits, banned phrases) are enforced by the test harness in code. The raw outputs and judge verdicts are downloadable.
More writing emails head-to-heads: GLM 5.2 vs GPT-5.3-Codex · GPT-5.3-Codex vs Grok 4.5 · GLM 5.2 vs GPT-5.6 Sol · GPT-5.6 Sol vs Grok 4.5 · GLM 5.2 vs GPT-5.5 · GPT-5.5 vs Grok 4.5
Full ranking: Best AI for writing emails · model pages: GLM 5.2, Grok 4.5