MYOB AR - Email not sent - Unsupported Outlook Version - asking to switch to Outlook Classic

Caitlin_G​ ChrissyK1​ : ChatGPT explains in more detail (point 2 does not apply here):

Microsoft's New Outlook (the redesigned version for Windows and Mac) is unsupported by many third-party software programs — especially email-sending add-ins or integrations — because of major architectural and API changes compared to Classic Outlook (Win32 desktop version). Here's a breakdown of why:

🔧 1. New Outlook uses a web-based architecture

• New Outlook is built on the same web technology as Outlook for the web (OWA).
• It lacks full access to the COM/VSTO (Visual Studio Tools for Office) APIs that most traditional Outlook add-ins and integrations rely on.
• Many software tools were built using COM-based plugins, which only work with Classic Outlook.

🧩 2. Limited or no support for legacy add-ins

• Add-ins created for Classic Outlook don’t work in New Outlook unless they're re-developed as Outlook Web Add-ins using Office.js (Microsoft's JavaScript-based API).
• These modern add-ins are sandboxed, meaning they have limited access to local system resources and other Office applications.

📭 3. MAPI & Extended MAPI not supported

• Many third-party apps (e.g., accounting tools, CRMs, backup software, etc.) send emails using MAPI (Messaging Application Programming Interface).
• New Outlook doesn’t support MAPI or Extended MAPI, so apps that use these APIs can't interact with it.
• Users will see errors or missing functionality when trying to send mail via New Outlook.

🧪 4. Feature parity is still incomplete

• Microsoft is gradually adding features to New Outlook but many are still missing or limited:
  • No support for .PST files
  • No support for POP accounts
  • No scripting or macros/VBA
  • No custom forms or custom UI extensions