Parcl

Secure Email Certificate Manager for Microsoft Outlook

Parcl is a Microsoft Outlook add-in that provides S/MIME email encryption, decryption, and digital signing with integrated certificate management and LDAP directory lookup.

Features

• Encrypt — Encrypt outgoing emails using recipient certificates
• Decrypt — Decrypt received emails using your private key
• Sign — Digitally sign outgoing emails
• Certificate Exchange — Send your certificate to recipients for secure communication
• Certificate Selector — Choose signing and encryption certificates from your local store
• LDAP Lookup — Automatically discover recipient certificates via directory services
• Options — Configure LDAP directories, crypto preferences, and add-in behavior

Architecture

src/
  Parcl.Addin/       # Outlook VSTO COM Add-in (Ribbon UI, dialogs)
  Parcl.Core/        # Core library (S/MIME, LDAP, cert management)
  Parcl.Installer/   # Per-user WiX installer (no admin required)
tests/
  Parcl.Core.Tests/  # Unit and integration tests

Requirements

• Microsoft Outlook 2016+ (desktop)
• .NET Framework 4.8
• Windows 10/11

Installation

Per-user install — no administrator privileges required. Registers under HKCU to avoid WOW6432Node registry issues.

Building

dotnet restore
dotnet build --configuration Release

License

MIT