Outlook Web - compose and verify one message

Notes an AI agent reads before it works on outlook.office.com: what to open, what to call, what breaks. Written by browser-harness contributors after real runs, and kept on GitHub under the MIT license.

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Give it to your agent

Any coding agent

Start the task with this line. The Markdown version is the same notes without the page around them.

Read https://browser-use.com/skills/outlook.md, then <your task>

Browser Harness

Save the files into your workspace and turn domain skills on. The code below calls its helpers, such as http_get and js. What Browser Harness is.

d="${BH_AGENT_WORKSPACE:-$HOME/.config/browser-harness/agent-workspace}/domain-skills/outlook"
mkdir -p "$d" && cd "$d"
curl -sLO https://raw.githubusercontent.com/browser-use/browser-harness/main/agent-workspace/domain-skills/outlook/webmail-compose.md
export BH_DOMAIN_SKILLS=1

Route and compose controls

Mail: https://outlook.office.com/mail/.
Recipient editors: [contenteditable=true][aria-label="To"], with separate Cc and Bcc editors.
Subject: input[aria-label="Subject"].
Body: [contenteditable=true][aria-label="Message body"].
Recipient entities render as span._Entity[aria-label]; inspect each recipient field separately before sending.

First-use UI and recipient handling

A first-use privacy dialog can appear after the initial inbox has loaded. Dismiss its Continue button before opening compose. A loaded inbox alone does not prove the compose controls are unobstructed.

Typing an address initially leaves the recipient suggestion open. Select the displayed address suggestion and verify that a recipient entity was created before moving to the subject. The popup can cover the subject input.

Do not emit a literal tab character when moving between recipient fields. Some keyboard helpers send a char event for Tab as well as key events; Outlook can store that character as an invalid empty recipient. Use raw Tab keyDown/keyUp events without text or char events.

The invalid-address banner offers Remove recipient, but inspect the editor afterward: a raw whitespace character can remain and recreate the invalid entry on the next send attempt. If ordinary editing fails, focus the affected editor. Create const range = document.createRange(), then call range.selectNodeContents(editor) for that editor. Clear window.getSelection() with removeAllRanges(), then add the range with addRange(range). Then call document.execCommand('delete'). This cleared the editable content in the observed browser. Verify the editor contents afterward. Recheck every recipient field before sending.

Verification

Successful sending closes compose and removes the draft. Confirm the exact subject and recipient in Sent Items before claiming it was sent or retrying. Sent Items confirms submission; recipient-side delivery and SPF/DKIM/DMARC results require separate recipient-side evidence.

webmail-compose.md · updated Oct 9, 2026 · 282 words

Sites change. These notes describe what worked when they were last updated, not a guarantee they still do. If something broke, the fix is a pull request to browser-harness.