After Office update, attachments in Outlook Rich‑Text Format (RTF) emails have display issues

Since you are using English on a Chinese forum, I will reply in English to make communication easier. If you would like me to use a different language, please let me know. 

Hi,

The image shows that the embedded attachment location is present in the Rich Text Format email body, but the expected Excel attachment icon is not rendering correctly.

We checked the referenced Office build. Version 2608 Build 20326.20100 is listed by Microsoft as a Current Channel (Preview) build released on August 18, 2026, with the release note “Various fixes to functionality and performance.”

To learn more, please visit:

• Release Notes for Office Current Channel (Preview)
• Fixes or workarounds for recent issues in classic Outlook for Windows

This behavior appears to be related to how Outlook renders attachments embedded in RTF messages. In Outlook, RTF messages can place attachments directly in the message body, while HTML or plain text messages typically handle attachments differently. Please notes that attachment placement depends on the message format and recommends switching the compose format to HTML when attachments appear embedded in the message body.

Please try the following steps:

1. Open Outlook.
2. Go to File > Options > Mail.
3. Under Compose messages, change Compose messages in this format to HTML.
4. Reopen or recreate the message and attach the Excel file again.
5. If replying to an existing RTF email, go to the message ribbon and switch the format to HTML before attaching the file.

As a temporary mitigation, if the issue is blocking business use, Microsoft documents that Click-to-Run Office installations can be reverted to an earlier build when an update introduces unexpected behavior (You can find more information at: How to revert to an earlier version of Office). I recommends weighing this against the security, performance, and reliability improvements included in newer builds.

I hope this information is useful. Thank you again for your time and for raising this important usability concern. If you have any further questions or need additional assistance, please don’t hesitate to reach out. 

I look forward to your thoughts on this. 

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