Is there any error message while opening the PDF file?
Also, let me know if the PDF is created using Acrobat or some other tool?
Have you tried to open the PDF file on computer?
*Make sure that the updated version of the Adobe Acrobat Reader mobile app. is installed Adobe Acrobat Reader on the App Store on iTunes.
[discussion moved to the Reader/Acrobat DC for mobile forum]
When you open a PDF attachment on iPhone or iPad, it will be opened in Apple Mail preview (by default), which does not render annotations (e.g. Sticky Notes, Highlight, Freehand Drawing) or form fields.
Would you have your email recipients read the "Open from Mail" section of the following FAQ documents to open the PDFs in Acrobat Reader for iOS instead?
Please let us know if you have further questions. Thank you.
The PDF was created though a program created to Delphi using ShellAPI and
Program works great for everyone except Iphone users.
[email signature/personal information removed by moderator]
I believe that the problem occurs because the PDF attachment is opened in Apple Mail preview.
Would you have your email recipients follow the steps described in the FAQ documents above to open the PDF attachment in Adobe Acrobat Reader for iOS (instead of Apple Mail preview)?