Outlook .otf files open/usage errors

Question

My team is experiencing an issue with .otf files. We create file templates for our team to be able to download and send emails directly from the template file. We upload these files into SharePoint. It seems that when a file is downloaded, several people are all getting different results when they open the email. Some open it and it has the email template as well as random attachments on the email, others it force opens in New Outlook despite them using old outlook (and includes image files), for some, it doesn't open at all and for one (that we know of), it opens as code in notepad. 

Up to this point, we were not experiencing any issues, but this is a vital part of our team's process, so we are seeking out a solution. We are using Classic Outlook to create and save these email templates and do not intend to switch over to the New Outlook at this time.

Answer 1

Hi Julia,

The different behaviors (unexpected attachments, opening in New Outlook, failure to open, or opening in Notepad) are not due to a problem with the template itself, but rather how each user’s device and Outlook client is handling the .oft file after it is downloaded from SharePoint.

This type of behavior can vary because .oft files rely on:

• Local file associations on each device
• The Outlook client being used (Classic vs New Outlook)
• How the file is opened (browser vs local file system)

As a result, users may experience different outcomes depending on their environment.

To ensure consistent behavior across your team, please follow the steps below:

1. Download the file before opening

• From SharePoint, select the template and choose Download
• Avoid opening the file directly from the browser

2. Ensure the file opens with Classic Outlook

• Right-click the downloaded .oft file > Open with
• Select Outlook (desktop / Classic Outlook)
• If needed, set this as the default app for .oft files

Incorrect associations (e.g., Notepad or browser apps) can result in the file opening as code or failing to open.

Some users may be redirected to the New Outlook experience, which handles templates differently and may convert embedded images into attachments and pen templates incorrectly since New Outlook only partially support opening .oft files

For more information. please consult: Feature comparison between new Outlook and classic Outlook - Microsoft Support

For the most consistent results, I recommend opening templates directly from Outlook instead of double-clicking files:

1. Open Outlook
2. Go to Home > New Items > More Items > Choose Form
3. Select User Templates in File System
4. Browse to the downloaded template and open it

This method bypasses browser and file association limitations.

I hope this provides enough clarity and helps you stay inform with your current situation.

In the meantime, if you see my replies bring helpful information, please kindly accept it as an answer and vote it up by your original account, which raised this question. Once marked, it will automatically pin to top. As other users will also search information in this community, your valuable vote up will definitely also help other users who have similar queries easily to find the correct channel and useful information more quickly.   

 

Thank you for your patience and your understanding. If you have any questions or need further assistance, please feel free to share them in the comments on this post so I can continue to support you.   

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Answer 2

The behavior described matches known issues with Outlook template files (.oft), especially when combined with different Outlook versions and recent Windows/Office changes.

Key points from known issues:

1. Outlook sometimes fails to open .oft files correctly
   • Outlook for Microsoft 365 has had issues where .oft and .msg files do not open properly when Outlook is running, or they trigger crashes or unexpected behavior after certain Windows updates.
   • Symptoms can include failure to open, odd behavior when opening from file locations (including SharePoint sync folders), or needing Outlook to be closed first.
   • This issue was fixed in later Office builds; older builds may still show inconsistent behavior.
2. New Outlook vs Classic Outlook
   • New Outlook is not MAPI‑compliant. It cannot reliably be used as the default mail client for operations that rely on MAPI, such as sending files directly from Office apps or some template‑based workflows.
   • When the system or Office apps try to resolve a default mail client, they may invoke New Outlook even when Classic Outlook is preferred, which can cause inconsistent behavior when opening .oft files.
3. Outlook 2010 + .oft templates (if any users are on 2010)
   • Outlook 2010 has a known issue where messages sent from .oft templates may not behave correctly when Outlook is configured in online mode with a .pst as the default delivery location. Although this is about sending rather than opening, it shows that .oft handling is fragile in older Outlook versions.
4. Attachments and blocked/altered content
   • Outlook and Exchange/Outlook on the web can block or treat certain file types differently for security reasons. Depending on policy and client, attachments may appear, be blocked, or be handled differently.

Recommended actions for the team’s scenario:

1. Standardize on Classic Outlook and supported builds
   • Ensure all users who work with the templates use Classic Outlook, not New Outlook, as their active mail client.
   • Verify that Office/Outlook is updated to a build that includes the fix for .oft/.msg opening issues (for Microsoft 365, this is in Current Channel Version 2004 (Build 12730.20236) or later, and corresponding fixed builds for other channels and perpetual versions).
2. Avoid using New Outlook as default mail client
   • Ensure New Outlook is not set as the default mail client on users’ machines. Because New Outlook is not MAPI‑compliant, it can cause failures or odd behavior when opening or using .oft templates from other apps or from the file system.
3. Re‑create templates if corruption is suspected
   • If specific .oft files consistently show random attachments or open incorrectly, re‑create those templates in Classic Outlook and re‑upload them to SharePoint.
4. Test opening behavior with Outlook closed vs open
   • If some users can only open .oft files when Outlook is closed, this aligns with the known .oft/.msg issue. Confirm that those users are on updated Office builds; if not, update them.
5. Consider avoiding .oft templates where possible
   • For environments where .oft behavior remains unreliable, one documented workaround is to avoid .oft files and instead copy the template text into a new email message. This removes the template file dependency and avoids many of the client/version issues.
6. Check attachment/security policies if attachments differ
   • If some users see extra or missing attachments, review any Exchange/Outlook on the web mailbox policies or security tools that might be altering or blocking certain attachment types. Policies that block or treat some file types differently can lead to inconsistent attachment behavior across users.

These steps focus on ensuring all users are on a fixed, supported Classic Outlook build, avoiding New Outlook for template workflows, and minimizing reliance on .oft where it remains unreliable.

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References:

• Email messages aren't sent when you use a template file in Outlook 2010
• Outlook stops opening .msg and .oft template files
• Blocked attachments in Outlook
• Office file links and attachments in Outlook Desktop show to be in Protected View but do not open
• Office 365 apps insist on using Outlook Classic to share documents to email - Microsoft Q&A
• I am unable to share my file either as a presentation or document type or pdf type by none of the microsoft office apps (Word, Excel, Powerpoint). It is continuously showing "Mapi Failure" and "Unable to Share" errors. What can I do? - Microsoft Q&A