Best AI tool for writing emails

An email is a short piece of writing with a reader who can tell when the voice is wrong. The best AI tool for writing emails is the one you would trust with that voice, not the one with the most features in the reply. The ranked list is Best for Writing. This page applies that list to a note you will actually send. It does not quote a subscription price, and it does not claim a hidden Gmail integration we have not described on the ranking.

The longer writing comparison, which covers essays and rewrites as well as mail, is Best AI writing tool. If the job is code rather than a note, leave this page. That comparison is ChatGPT vs Claude for coding.

Sound like a person

Claude (opens in a new tab) is the first editorial pick for a long draft that has to sound like a person, and a careful email is the short version of that job. You paste the context, you say who is reading, and you ask for the note. The failure mode on this list is the opposite of a stiff template: Claude is weaker when the job is searching the web and citing this afternoon's news. An email that needs today's fact, with a link, is a research job first. Write the fact somewhere you can check, then bring the sentence back.

Claude Haiku 5.5, launched 7 October 2026, is the cheap high-volume model in the same family. Anthropic's product page calls it the cheapest, fastest, and most capable small model the company has released, with a 1 million token context window. That note is Claude Haiku 5.5 is Anthropic's new small model. It is not why Claude is first here. Use the small model when you are sending a pile of similar notes and the voice is already decided. Use the writing rank's reason, the draft that sounds like a person, when one email has to carry the relationship.

The generalist rewrite

ChatGPT (opens in a new tab) is second. It is still the generalist for drafts and rewrites. As of the 7 October 2026 rollout, ChatGPT can answer with GPT-6 Intelligent UI: text plus charts, buttons, and small tools in the reply. Plus, Pro, Business, and Enterprise use GPT-6 Sol. Free and Go use GPT-6 Luna. The detail is GPT-6 brings Intelligent UI to ChatGPT. OpenAI says the models behind Work and Codex are not part of that release.

For an email, most of that interface is beside the point. You need a paragraph, not a chart. The default voice is still even, and a careful draft still wants an edit. ChatGPT is the right second pick when you already live in it and the note is ordinary: a scheduling reply, a status update, a rewrite of a paragraph you do not like. It is the wrong pick when the only requirement is that the note sound like you on a sensitive thread. That is the first rank.

Next to the inbox

Gemini (opens in a new tab) is third. It is convenient when the draft lives next to Gmail and Docs. That convenience is the whole argument for writing the email there: the thread is already open, and you are not pasting between tabs. For ordinary prose the voice is still flatter than Claude. Google AI Pro and Ultra subscribers can also use Gemini 4 Argon here. Argon, generally available on 13 October 2026, is the frontier model for hard coding, science, and agent work, not a reason to move a normal memo. If the words have to sit in a Google file you already share, Gemini's convenience can beat a better voice that you would only paste in later. If the words have to sound like a person, start in Claude and paste the result.

Edit what you already wrote

Grammarly (opens in a new tab) is fourth. It is an editor, not a writer. Use it to catch tone, clarity, and grammar on text you already wrote. Generating the piece from scratch is not why it earns a spot. For email, that is often the last pass: you wrote the note, or Claude did, and you want a check before send. It is a poor place to invent the message.

Notion AI (opens in a new tab) is fifth. It is worth it when the document is already in Notion and you want a summary, a rewrite, or a messy page cleaned up in place. A mail client is not that place. Do not start an email there unless the source material already lives on the page.

What to open

If the email has to sound like a person, open Claude. If you want a generalist rewrite and you already have ChatGPT open, stay there and edit the even voice. If the thread is already in Gmail, Gemini is the convenient third, not the better prose. If the words exist and you only need a check, use Grammarly. The rank numbers live on Best for Writing.