Gemini is the best AI for email, because it is already in Gmail, on the thread you have open. ChatGPT, Claude, and Grok can write a strong reply. You have to carry the email over to them first.
Use Gemini in Gmail, and use CMDK for the rest of the speed: shortcuts, a command bar, snippets, and read receipts in the same window.
The short version
| Best at | Where you use it for email | Your mail | |
|---|---|---|---|
| Gemini | The thread in front of you | Inside Gmail | Stays with Google, which already has it |
| ChatGPT | A blank-page draft, a rewrite, a tone change | A separate chat. You paste the mail in | A copy goes to OpenAI |
| Claude | Long threads and careful wording | A separate chat. You paste the mail in | A copy goes to Anthropic |
| Grok | A fast, blunt take | grok.com or X. You paste the mail in | A copy goes to xAI |
Gemini
Gemini can see the thread, the people on it, and the files already in your Google account. Ask it to summarize the chain, pull out the ask, or draft the reply, then edit the draft in Gmail and send it yourself. You are not exporting the mailbox to a second company. Google already holds the mail. Gemini is Google reading it back to you.
That is the whole advantage. The writing is good. The location is the reason it wins for email. A reply drafted beside the thread is faster than a reply drafted in another tab that has never seen the previous eight messages.
Gemini is not on every free Gmail account. If the side panel is missing, it is a Google account setting, not something CMDK turns off. CMDK can hide the Gemini button if you ask it to, under Appearance. Leave that toggle off if you want Gemini in the toolbar.
ChatGPT
ChatGPT is the strongest of the four when the email does not exist yet. A cold note, a tricky apology, a rewrite in a plainer voice: paste the facts in and it will produce options. It is a poor inbox, because it does not have your inbox. Every thread you want help with is a copy you paste, and that copy is now in OpenAI’s hands as well as Google’s.
Use it for the rare message where the wording is the hard part. Do not use it as the place you read mail.
Claude
Claude is the one to open when the thread is long and the reply has to be precise. It holds a lot of context and it is careful about what you asked it not to say. Same limit as ChatGPT: the mail is not there until you paste it, and then Anthropic has that paste. For a contract argument or a note you will be quoted on, that extra care is worth the tab. For Tuesday’s normal mail, it is a detour.
Grok
Grok is quick and it will be more direct than the other three, which helps when a draft sounds stiff. It has no Gmail. You paste, you copy back, you hope you did not drop a sentence. Fine for a one-off. A bad daily driver.
Use Gemini inside Gmail, with CMDK
An assistant that reads the whole inbox and files it for you is a different product. CMDK vs Cora is that comparison. The model should sit where the mail sits. That is Gemini. CMDK does not replace it and does not send your mailbox to another AI. It makes the Gmail around Gemini faster: a command bar, shortcuts, snippets you insert yourself, split inbox, snooze, reminders, and read receipts. The setup is the same idea as making Gmail work like a fast client, with Gemini left in the page.
A practical split:
- Summarize and draft with Gemini, in the thread.
- Send, snooze, file, and jump around with CMDK.
- Open ChatGPT or Claude only when one message needs a rewrite you do not want Gemini to do.
- Skip Grok unless you already live in it.
You do not need four subscriptions to answer email. You need the model that can see the thread, and a faster Gmail around it.
Frequently asked questions
Which AI is best for email?
Gemini. It is the one that can read the open Gmail thread without you pasting it into another product.
Does Gemini work inside Gmail?
Yes, on Google accounts that include it. It opens on the side of the message. CMDK does not block it unless you hide the Gemini button in Appearance.
Should I paste email into ChatGPT or Claude?
Only for a single hard draft. Both can write well. Both mean a second company now has that mail. Gemini does not add a new company.
Does CMDK replace Gemini?
No. CMDK is shortcuts and Gmail tools. Gemini is the writing assistant. They run in the same Gmail window.
Does Grok connect to Gmail?
Not as a Gmail sidebar. You paste the message in. That is a worse loop than Gemini for everyday mail.
Install CMDK and keep Gemini in the same Gmail. The trial is 15 days and does not ask for a card.
