Error message when you try to use Outlook to perform an action on a calendar meeting item: "This message could not be sent because it exceeds the maximum size allowed"

When you try to use Microsoft Outlook to perform an action on a calendar meeting item in a Microsoft Office 365 environment, you receive the following error message:

This error occurs�if one of the following conditions is true:

• One or more file attachments in the meeting item made the message size too large.
• The reminder for the meeting item is corrupted.

To fix this issue, delete that particular meeting item by using Microsoft Exchange Server MAPI Editor (MFCMAPI). To do this, follow these steps.

Note Although the MFCMAPI tool is supported by Exchange Online, we recommend that you always use caution when you modify mailboxes by using this tool. Using the MFCMAPI tool incorrectly can cause permanent damage to a mailbox. Confirm that Outlook is set to use Cached Exchange Mode before you perform this procedure.

1. Download and install MFCMAPI from the following Microsoft CodePlex website:
   http://mfcmapi.codeplex.com
2. In Outlook, on the Send/Receive tab, click Work Offline, and then exit Outlook.
   
   
3. Start MFCMAPI.
4. On the Session menu, click Logon and Display Store Table.
   
   Note The exact steps will vary based on the version of MFCMAPI that you're using.�
   
   
   
   
5. If you have more than one mail profile, right-click the mail profile for which the Display Name column shows Mailbox-<Your_Name>, and then click Open Store.
   
   
   
   
6. Expand Root-Mailbox, and then expand Finder.
   
   
   
   
7. Double-click Reminders. A new window opens.
   
   
   
   
8. Locate the recurring appointment by sorting the Subject column or the To column.
   
   Right-click the appointment, and then click Delete Message.
   
   
   
   
9. A dialog box appears. In the Deletion style list, select Permanent delete passing DELETE_HARD_DELETE (unrecoverable), and then click OK.
   
   
10. Close the MFCMAPI dialog boxes.
11. Click Start, click Run, type outlook.exe /cleanreminders, and then click OK.
    
    
    
    
12. If you're prompted, select your profile to start Outlook.

Still need help? Go to the Office 365 Community website.