Hello, @Matt Johnston,
Welcome to the Microsoft Q&A platform!
The error message you're seeing, "Task 'Microsoft Exchange Server - Sending' reported error (0x80040610): 'The message being sent exceeds the message size established for this user,'" typically indicates that the email you're trying to send is larger than the maximum size allowed by your email server.
Here are some steps you can take to resolve this issue:
1.Check Your Drafts and Outbox: Make sure that there aren't any large messages stuck in your Drafts or Outbox folders. These could be causing the error to repeatedly trigger. If you find any large messages there, try deleting them or splitting them into smaller parts. A previous customer solved the problem by deleting these emails.
2.Adjust the Message Size Limit on the Server: If you have administrative access, you can adjust the message size limit on the Exchange server. This typically requires changes to the Exchange Management Console or the Exchange Admin Center. If you do not have administrative access, you may need to contact your IT administrator to request this change.
3.Reduce Attachment Sizes: If you're frequently sending large attachments, consider using alternative methods to share large files, such as cloud storage services (e.g., OneDrive, Google Drive, Dropbox) and sharing links instead of attaching large files directly to emails.
4.Repair Your Outlook Data File: Use the Inbox Repair Tool to repair your Outlook data file. This tool can fix various issues related to your PST file.
5.Clean Your Mailbox: In Outlook, go to the File menu, select Tools, and then Clean Up Mailbox. This can help remove any unnecessary items that might be causing issues.
6.Recreate the Outlook Profile: Try recreating your Outlook profile. Go to Control Panel > Mail > Show Profiles, create a new profile, and configure it with your email account (Instructions: https://support.microsoft.com/en-us/office/create-an-outlook-profile-f544c1ba-3352-4b3b-be0b-8d42a540459d). Open Outlook with this new profile and see if the issue persists.
(*Note: Remember to back up any important data before making major changes to your Outlook configuration.)
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Thank you for your support and understanding.
Best Wishes,
Alex Zhang