It sounds like you're encountering a complex issue with forwarded emails in your hybrid cloud/local environment. Here are some steps you can take to troubleshoot and potentially resolve the issue:
Check Email Rules and Filters: Ensure that there are no email rules or filters set up in Outlook or on your email server that might be causing the content of forwarded emails to be removed. Sometimes, automated rules can inadvertently strip email content.
Review Exchange Server Settings: Since you're in a hybrid environment, review the settings on your Exchange server to see if there are any configurations or policies that could be affecting forwarded emails.
Inspect Email Headers: Examine the email headers of the forwarded emails to see if there are any clues about what might be causing the issue. Look for any unusual modifications or inconsistencies in the headers.
Check Antivirus/Anti-spam Settings: Verify that your antivirus or anti-spam software is not interfering with forwarded emails. Sometimes, security software can mistakenly flag forwarded emails as suspicious and remove their content.
Test Different Email Clients: Since you mentioned that the issue seems to occur inconsistently across different email clients (desktop Outlook, web Outlook, mobile), test forwarding emails using different clients to see if the behavior is consistent or if it varies depending on the client used.
Monitor Email Traffic: Keep an eye on email traffic and monitor the issue closely to see if you can identify any patterns or commonalities among the affected emails. This might help pinpoint the root cause of the problem.
Consult with Microsoft Support: If you're unable to resolve the issue internally, consider reaching out to Microsoft Support for assistance. They can provide specialized guidance and assistance for troubleshooting issues in hybrid environments.
Update Exchange Server and Outlook: Ensure that your Exchange server and Outlook clients are running the latest updates and patches. Sometimes, software bugs or compatibility issues can cause unexpected behavior that is resolved in newer versions.