Using New Outlook on Windows for professional communication and productivity
For Outlook on the web on a Windows 10 PC, the most relevant checks are:
- Test in a different browser or an InPrivate/Incognito window. If attachments open there, the issue is likely browser-related.
- If the same attachment works on the phone but not on the PC, try a different network on the PC, such as a mobile hotspot. If it works there, a firewall, proxy, or network restriction is likely interfering.
- If the issue affects only certain file types in Outlook on the web, the Outlook on the web mailbox policy may be blocking those file types. An admin can change the Outlook on the web mailbox policy to allow or block specific file types. Note that policy changes can take several minutes to take effect, and allowing blocked file types can increase security risk.
- If the mailbox policy cannot be changed, a supported workaround is to compress the file, such as into a .zip file, and send it as an attachment.
- If the issue is urgent, use another client as a workaround:
- If classic Outlook is available, open or download the attachment there.
- For some Exchange Server OWA scenarios, using the OWA light version by adding
?layout=lightto the additional mailbox URL is a documented workaround.
If this is classic Outlook rather than Outlook on the web, and the problem is previewing Office attachments on Windows 10, make sure the Windows Firewall service is running:
- Press Windows key + R.
- Type
services.mscand select OK. - In Services, right-click Windows Firewall and select Properties.
- Set Startup type to Automatic and select OK.
- Right-click Windows Firewall and select Start.
Also in classic Outlook, verify preview is enabled:
- Go to File > Options > Trust Center > Trust Center Settings.
- Select Attachment Handling.
- Make sure Turn off Attachment Preview is not enabled.
- Can't open or view attachments in Outlook on the web
- Can't preview Office documents in Outlook if Windows Firewall Service is disabled
- Open, save, and edit attachments received in Outlook
- Attachments can’t be downloaded or previewed from Outlook Web App
- Outlook web attachment not open and can't download - Microsoft Q&A