Fix Acrobat Reader Cannot Open PDFs or Winmail.dat Files on Mac
Question details
User is experiencing intermittent failures when trying to open PDF files or print documents using Acrobat Reader on a Mac, sometimes encountering errors stating that winmail.dat is unsupported or damaged.
- Product
- Adobe Acrobat Reader
- Device & OS
- iMac (macOS)
- Scenario
- Attempting to open email attachments or local PDF files and trying to print documents.
- Observed behavior
- Acrobat Reader fails to open the files, cannot print, or displays an error stating that the winmail.dat file is unsupported or damaged.
Ensure your Mac's macOS is up to date and check if the problematic file can be temporarily previewed using Mac's built-in Preview app before proceeding with troubleshooting.
Verify File Format and Save the File Locally
Email clients sometimes misconfigure attachments as winmail.dat files, which standard PDF readers cannot process. Saving the file locally helps rule out email client conflicts.
A winmail.dat file is a proprietary Microsoft Exchange format. If you receive this instead of a PDF, it means the sender's email client formatted the message in a way your Mac's mail app couldn't decode properly.
Look at the attachment's name. Ensure it ends in .pdf and not .dat.
Instead of opening the file directly from your email client, click 'Download' or 'Save As' to save it to your Mac's Desktop or Downloads folder.
If you are certain the winmail.dat file is actually a PDF, try clicking the filename, renaming the extension from .dat to .pdf, and confirming the change.
Right-click the saved .pdf file, select 'Open With', and choose your preferred PDF reader to test.
Update or Reinstall Adobe Acrobat Reader
Outdated or corrupted software installations can cause intermittent opening and printing failures.
Test with an Alternative Viewer
If the file is damaged during transmission, no reader will open it. Testing with another app confirms if the file itself is the problem.
Try WPS Office as a Reliable PDF and Document Viewer for Mac
If you frequently encounter issues with unsupported formats or bloated software, WPS Office provides a lightweight, all-in-one solution for Mac. It seamlessly handles PDFs, Word documents, Excel spreadsheets, and PowerPoint presentations with high performance and stability.
- 1. Download the Mac version: Visit the official WPS Office website and download the installation package for Mac.
- 2. Install the software: Open the downloaded installer and drag the WPS Office icon into your Applications folder.
- 3. Open your files: Launch WPS Office and set it as your default PDF viewer to enjoy smooth, error-free document handling.
Frequently Asked Questions
What is a winmail.dat file and why is it on my Mac?
A winmail.dat file is a proprietary attachment format used by Microsoft Outlook and Exchange servers. When an email is sent in Rich Text Format, non-Outlook email clients (like Apple Mail) cannot decode the formatting, resulting in a winmail.dat attachment instead of the intended file.
How can I extract a PDF from a winmail.dat file?
You can use third-party extractor tools or specialized websites designed to decode winmail.dat files. Alternatively, if you are certain the attachment is a PDF, you can try saving the file locally and changing the file extension from .dat to .pdf.
Why does my PDF reader crash when I try to print on a Mac?
Printing crashes on a Mac can be caused by outdated printer drivers, corrupted preference files, or a missing font within the PDF. Updating your Mac's printer drivers and ensuring your PDF reader is updated to the latest version usually resolves this issue.
Can Mac's built-in Preview app open winmail.dat files?
No, Apple's built-in Preview app does not natively support winmail.dat files. It handles standard image and PDF formats. You will need a specific winmail.dat extractor or the sender needs to resend the email in Plain Text or HTML format.
