Hi Georgina
Good day to you!
Thank you for reaching out to Microsoft Support.
We're sorry to hear you're experiencing this issue. We completely understand how frustrating it can be, and we sincerely apologize for the inconvenience.
To assist you better, we’d like to clarify a few details so we can determine the right next steps:
- Which version the issue occurs on (New, Classic, or Web). Have you tried all three versions?
- Have you tried logging in with another account? Do you have the same problem?
- Have you tried logging into other Microsoft office apps? Do you get the same error?
- When you mention the "Error 500 message," could you please click Show more details and share a full screenshot with me?
- Also, do you know if other users in your organization are experiencing the same issue? Does it happen with multiple recipients or only with a specific one?
Once we have this information, we’ll be in a better position to identify the cause and guide you toward a solution.
We hope this helps clarify the situation. Please feel free to reply with the requested details so we can continue assisting you.
Looking forward to your response!
Warm regards,
Jason-NP – MSFT | Microsoft Community Support Specialist