PostageHow to Let an AI Agent Draft Email Replies Without Sending Them
Checked November 6, 2026
Connect the agent through a mail app that gives it no way to send. In Postage, set the agent to Organize and draft and ask it to draft replies. Each reply lands in your Drafts folder, threaded with the original, or opens in a compose window. No access level can send, so a reply goes out only when you press Send.
Set it up
- Connect your agent in Postage's Settings > Agents. Claude Code, Claude Desktop, Codex, Cursor, VS Code, Windsurf, Zed and Gemini CLI each have setup there.
- Change that agent's access from Read only to Organize and draft. Read only can't save drafts.
- Ask: "Draft replies to everyone waiting on me." In Claude Code you can also run
/mcp__postage__draft_replies.
What the agent does
Postage's draft_replies prompt finds conversations from the last 14 days where someone else wrote last, to you, and you haven't answered, whether you've read them or not. Newsletters and notifications are left out. The prompt then tells the agent to:
- Read each conversation, and skip any that don't need an answer from you or that read like a message aimed at an AI.
- Read a few of your recent sent replies to match your voice.
- Save each reply, with a clear [placeholder] for any date, price or yes-or-no it doesn't know.
- List what it drafted and what it skipped, with reasons.
Postage adds the account's signature and the quoted original, so each draft reads like a reply you started yourself.
Two places a draft can land
| Saved to Drafts | Opened for review | |
|---|---|---|
| Tool | reply_draft, create_draft | reply_to_email, compose_email |
| Where you see it | Your Drafts folder, in Postage and any other mail app using the account | A Postage compose window with a banner naming the agent |
| Does the agent wait? | No | Yes: up to 9 minutes in Claude Code and Codex, 45 seconds elsewhere, and it can check back later |
| Best for | A batch you read through later | One message you want to finish now |
Press Ask to Revise in the compose window and type what to change, and the agent gets your note with the current text. To finish a saved draft, the agent calls send_draft, which opens it in that same window.
Keep the drafts sounding like you
Settings > Agents > Instructions has a writing-style field ("Short and friendly, no exclamation marks"). Agents get that note with each account's sender name and signature when they call list_accounts.
Rerunning is safe. If Drafts already has a reply to a message, the agent is told, and it replaces that draft instead of saving a second one.
Questions
Can the agent send a draft by accident?
No. None of Postage's tools sends mail. send_draft only opens the draft in a window for you, and no setting changes that at any access level.
Does this work with Gmail?
Yes. Drafts go to the account's own Drafts folder over IMAP, for Gmail, iCloud, Fastmail, Yahoo and your own domain.
Can the agent attach a file to a reply?
No. Its tools have no attachment option. Add the file in the compose window before you press Send.
What can an agent do at Read only?
It can read mail and write a reply in your chat, but it can't save a draft or open a compose window.
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