OneNote email page issue

The .mht attachment usually indicates that OneNote is handing the page to Outlook in a web-page/MHTML format rather than inserting the page content directly into the email body. Since you have already performed both Quick Repair and Online Repair, I would not reinstall or reformat the system yet.

One important thing to check first is which Outlook client is being used. Microsoft currently states that the OneNote Email Page experience is supported in Classic Outlook, while the equivalent functionality is not currently supported in New Outlook for Windows.

If you are using Classic Outlook, try these fixes in this order:

1. Make Classic Outlook the default mail application. Go to Windows Settings → Apps → Default apps → Outlook and make sure Outlook is the default for mail-related protocols/file types. Microsoft Q&A has specifically identified incorrect default-mail-app registration as a cause of OneNote sending the page as an .mht attachment.
2. Check OneNote's email settings. In the desktop OneNote application, go to File → Options → Advanced and look for the Email sent from OneNote section. There is an option concerning attaching embedded files to the email as separate files; if it is enabled, make sure it is unchecked, then restart OneNote and Outlook. A Microsoft Q&A response from February 2026 specifically suggested checking this setting for the .mht behavior.

Check Outlook's message format. The important distinction is that OneNote needs to create an HTML-format message for the page content to appear in the email body. A Microsoft Q&A case with essentially the same symptom found that the affected computer was creating the message as Plain Text, while a working computer created it as HTML.

In Classic Outlook, check File → Options → Mail → Compose messages in this format and select HTML.

1. Test with a completely new OneNote page. Create a simple page containing only a few lines of text and choose Email Page. If the new page works but your original page produces .mht, the issue may be related to content embedded in that particular page.
2. Test Classic Outlook directly. If you have both New Outlook and Classic Outlook installed, close New Outlook and use Classic Outlook for the OneNote test. Microsoft's current guidance confirms that OneNote's Email Page functionality is available in Classic Outlook, whereas New Outlook does not currently support the same experience.
3. If the problem continues, check the Outlook registration. Microsoft support guidance for this exact symptom has also recommended checking whether Outlook is properly registered as the default mail application. This involves Windows default-app settings and, in some cases, Office registration. Registry changes should only be made carefully and after creating a backup because an incorrect registry modification can cause other problems.

Most likely fix

Because you've already completed Online Repair, I would try these three things first:

Classic Outlook → make it the Windows default mail app → make sure OneNote's “Attach embedded files…” option is unchecked → make sure Outlook composes messages in HTML.

Then completely close OneNote and Outlook, reopen Classic Outlook first, open OneNote, and test Email Page again.

If it still creates an .mht, the next thing I'd check is whether your Office build is using Classic Outlook or New Outlook, because that distinction is particularly important with this feature. Microsoft currently recommends using Classic Outlook specifically when you need the OneNote Email Page workflow.

Dear @Sapna Rani Thanks for quick replying. I have already checked this setting it has already unchecked and already performed the same steps. I have mentioned the link which troubleshooting steps link already done on the machine.

Thanks for confirming. Since you have already tried those settings and completed both Quick Repair and Online Repair, I agree that repeating the same steps would not be useful.

At this point, I would suggest checking whether the issue is specific to the current Office/Outlook integration rather than the OneNote setting itself. Could you please confirm whether you are using Classic Outlook for Windows or New Outlook?

If you are using Classic Outlook, another useful test would be to try OneNote → Email Page with a newly created, very simple OneNote page containing only plain text. This can help determine whether the .mht behavior occurs with every page or only with a particular page.

If it happens even with a new plain-text page in Classic Outlook, please let me know. We can then focus on the Outlook/OneNote registration or Office build rather than repeating the settings you have already checked.

Dear @Sapna Rani , thank you for helping to resolve this issue.

I tested creating a sample OneNote page using plain text, but the issue still persists.

Please help share steps for registration of Outlook/OneNote.

Thanks once again.

Dear @Sapna Rani , thank you for helping to resolve this issue.

I tested creating a sample OneNote page using plain text, but the issue still persists.

Please help share steps for registration of Outlook/OneNote.

Thanks once again.