Microsoft is rolling out a new Copilot feature for Outlook on the web that lets you highlight a section of an email draft and ask the AI to rewrite it—changing its length, tone, or structure—all without leaving the compose window. Dubbed Co-Authoring Highlight and Rewrite, the feature entered general availability in July 2026 for worldwide standard multi-tenant customers, according to the Microsoft 365 roadmap (ID 564605).

What Changed: A Granular Rewrite Tool Arrives

The update adds an inline editing option to Outlook on the web. When composing or replying to an email, you can now select a specific sentence, paragraph, or even a few words, and call on Copilot to suggest improvements. The official roadmap entry, first created on May 26, 2026, and updated to “Rolling out” status on July 8, 2026, describes it plainly: “Users can select a section of an email draft and ask Copilot to help rewrite that selected text by changing its length, tone, or structure.”

That’s the entire pitch. It’s not a full-message generator, nor a one-click “make this email better” button. Instead, the feature acts like a surgical editing assistant that focuses only on the part you’ve highlighted. Microsoft’s examples—length, tone, structure—suggest practical uses: shorten a rambling update, soften a brusque request, or reorganize a confusing paragraph so the main point pops.

Who Gets It and When

The rollout is limited to Outlook on the web for commercial customers on the standard multi-tenant cloud. Microsoft’s roadmap specifically lists “Worldwide standard multi-tenant” as the cloud instance, with general availability set for July 2026. Roadmap entries are signals, not delivery guarantees, so while the feature is marked “Rolling out,” your tenant might not see it immediately. There’s no mention of on-premises, government, or sovereign cloud support yet, nor any promise of parity with the desktop, new Outlook for Windows, or mobile apps.

Admins should check directly in Outlook on the web for their organization. If a user asks why they can’t find the feature, the first troubleshooting step is to confirm they’re using the web version, not a desktop or mobile client. Licensing prerequisites aren’t spelled out in the roadmap, but the feature likely depends on your Microsoft 365 Copilot subscription tier. Test with a pilot group before broad communication.

How to Use Highlight and Rewrite Without Regrets

This tool fits neatly into your existing writing flow. Write your draft as you normally would, then look for the rough spots—a clunky sentence, a paragraph that’s too long, a closing that feels flat. Highlight the offending section, summon Copilot (the exact UI entry point isn’t documented yet, but typically a floating menu or toolbar icon appears), and choose a rewrite option.

Good instructions are short and specific: “Make this shorter,” “Make the request clearer,” “Sound more professional,” or “Reorganize so the action item comes first.” After Copilot serves up a revised version, compare it side-by-side with your original. Ask yourself:

  • Did the meaning survive the edit? A rewrite that turns “we can review next week” into “we will complete it next week” has changed your commitment.
  • Are all facts intact? Names, dates, dollar amounts, project codes—double-check them. AI doesn’t verify accuracy.
  • Does the tone still match the relationship? A warmer note shouldn’t slip into overfamiliarity; a formal note shouldn’t sound icy.
  • Is the structure still logical? If the rewrite moved sentences around, confirm that the most important point isn’t buried.
  • Have any new obligations crept in? Phrases like “I’ll take care of it” or “consider it done” can appear without your intent.

If anything’s off, either edit the suggestion manually or stick with your original. The golden rule: you’re the author, and you’re responsible for what gets sent.

Admins: Prepare Your Users for Inline AI Editing

For IT and Microsoft 365 admins, this rollout is less about flipping a switch and more about shaping user behavior. The roadmap doesn’t detail admin controls specific to Highlight and Rewrite—no tenant toggle, no separate audit log, no granular policy. Until you see otherwise, assume the feature piggybacks on your existing Copilot configuration.

Focus your energy on practical education. Start by confirming the feature’s presence in Outlook on the web for a test user. Then draft a short internal guide that covers:

  • Where to find it: Outlook on the web only; highlight text to see the Copilot rewrite option.
  • Appropriate uses: Shortening, softening, clarifying, or restructuring passages you’ve already written.
  • Risky territory: Rewriting contract language, HR statements, pricing commitments, incident reports, or any legally sensitive text. In those cases, a rewrite can inadvertently change meaning, so human review is mandatory.
  • The verification checklist: Meaning, facts, tone, structure, obligations—train users to run through it after every AI-assisted edit.

Equip your help desk with a simple script: “Are you using Outlook on the web? If so, highlight text and look for the Copilot icon. If not, the feature isn’t available yet on other clients.” This prevents wild goose chases and sets realistic expectations.

Keep an eye on Roadmap ID 564605 for scope changes. Microsoft sometimes expands client support or adds admin controls after initial rollout, so update your guidance when the facts change.

The Bigger Picture: AI Moves Closer to the Cursor

Highlight and Rewrite isn’t a flashy demo of fully autonomous email composition. It’s a quiet signal that Microsoft is weaving Copilot into the small, repetitive editing tasks that fill an office worker’s day. Most people don’t need an AI to write every email from scratch; they need help polishing the awkward parts that slow them down.

By operating on selected text, the feature hands control to the user. You decide what needs fixing, and you decide whether the fix is good enough. That boundary—selected text as the unit of AI assistance—reduces the risk of a wholesale rewrite introducing errors or straying from your intent.

The feature’s web-only launch also reveals Microsoft’s iterative approach. Outlook on the web serves as a testbed where updates ship faster and feedback loops are shorter. If Highlight and Rewrite proves popular, expect it to migrate to the new Outlook for Windows and eventually to the classic desktop app. But for now, treat it as a web-exclusive tool.

What to Watch Next

As the rollout continues, three threads deserve attention:

  1. Client expansion: Will Microsoft announce support for Outlook desktop, mobile, or specialized clouds? Roadmap updates will be the first sign.
  2. Admin controls: Demand for finer governance—like disabling only the rewrite feature while keeping other Copilot experiences—may push Microsoft to add policy settings.
  3. User readiness: The real measure of success won’t be adoption numbers but whether employees learn to verify AI-assisted edits before hitting send. Watch for help-desk tickets about unintended tone shifts or factual slips; those are teachable moments.

In the meantime, if you’re a regular Outlook on the web user, the next time you stare at a shaky paragraph, highlight it and see if Copilot can lend a hand. Just remember: the send button is still yours.