OutlookAI

An AI-powered email writing assistant for Microsoft Outlook, built as a VSTO add-in.

Features

• Quick Actions - One-click buttons to improve your email drafts:

  • Proofread (grammar, spelling, punctuation)
  • Revise (clarity and flow)
  • Shorten / Lengthen
  • Formal / Friendly tone

• Draft New Emails - Describe what you want to write and let AI generate the email

  • Voice input support using OpenAI Whisper
  • Context-aware replies (AI sees the email chain)

• Insert or Replace - Choose to add content at the top (preserving email chain) or replace everything

Requirements

• Windows 10/11 or Windows Server 2019/2022/2025
• Microsoft Outlook 2016, 2019, 2021, or 2024 (desktop version)
• .NET Framework 4.8
• Visual Studio Tools for Office Runtime

API Keys Required

This add-in requires:

• Anthropic API Key (Claude) - Required for all AI features. Get one at console.anthropic.com
• OpenAI API Key (Whisper) - Optional, for voice input. Get one at platform.openai.com

Installation

Option 1: Pre-configured Build (Enterprise/RDS)

1. Edit VSTO2\OutlookAI\Config.cs and add your API keys
2. Build the solution in Release mode
3. Publish from Visual Studio (Right-click project > Publish)
4. Copy the publish folder to your deployment location
5. Run Deploy\Install-OutlookAI.ps1 as Administrator:

Set-ExecutionPolicy -ExecutionPolicy RemoteSigned -Scope LocalMachine
Unblock-File -Path "C:\OutlookAI\Install-OutlookAI.ps1"
cd C:\OutlookAI
.\Install-OutlookAI.ps1 -SourcePath "C:\OutlookAI"

Option 2: Per-User Install

1. Build and publish the solution
2. Run setup.exe from the publish folder
3. Open Outlook and configure API keys in the Settings panel

Usage

1. Open Outlook and compose a new email (New, Reply, or Forward)
2. Click the AI Assistant button in the ribbon
3. The task pane opens on the right side

Quick Actions

• Write your email draft first
• Click any Quick Action button (Proofread, Revise, etc.)
• Review the result and click Insert or Replace

Draft New Email

• Type or speak your instructions (e.g., "Write a thank you email to John for the meeting")
• Click Draft Email
• Review and insert the result

Voice Input

• Click the red circle button to start recording
• Speak your instructions
• Click again to stop and transcribe
• Requires OpenAI API key

Building from Source

Prerequisites

• Visual Studio 2022
• Office/SharePoint development workload
• .NET desktop development workload

Build Steps

1. Clone this repository
2. Open VSTO2\OutlookAI\OutlookAI.sln
3. Restore NuGet packages
4. Build > Rebuild Solution

Configuration

Settings are stored in %APPDATA%\OutlookAI\config.xml

Access the Settings panel by clicking the gear icon in the add-in. The default admin password is admin.

Deployment Scripts

Located in the Deploy folder:

• Install-OutlookAI.ps1 - Per-machine install for all users (RDS/Terminal Server)
• Uninstall-OutlookAI.ps1 - Remove the add-in
• Enable-OutlookAI-User.ps1 - Re-enable if Outlook disabled the add-in

Troubleshooting

Add-in doesn't appear

• Restart Outlook
• Check File > Options > Add-ins
• Run Enable-OutlookAI-User.ps1

Add-in keeps getting disabled

• Outlook's "Resiliency" feature may disable slow-loading add-ins
• Run Enable-OutlookAI-User.ps1 or add it to logon scripts

"Untrusted" or security errors

• Ensure all files are unblocked (Right-click > Properties > Unblock)
• Or run: Get-ChildItem -Path "C:\Program Files\OutlookAI" -Recurse | Unblock-File

API errors

• Verify your API keys are correct
• Check your API account has credits/quota
• Ensure TLS 1.2 is enabled (default on modern Windows)

License

MIT License - See LICENSE file

Acknowledgments

• Anthropic Claude API - AI text generation
• OpenAI Whisper API - Speech-to-text
• NAudio - Audio recording