People receiving the file cannot open it. They never had problems with PDF files before
Answer # 1: "Hello: there is something wrong with your mail and/or the attachment. Not only I couldn't open it but also couldn't 'reply'. So please send again"
Answer # 2: "My computer says it needs to know what programme created the format before it will open it".
Answer # 3: "My compiuter cannot open this file - I have never had problems with PDFs before that I can remember. No explanation".
if it works on your computer, then the pdf is ok; make sure you tell them to have a pdf viewer installed (such as adobe reader - free) to be able to open the pdf. also if it takes long to be emailed its size probably is quite large, so you might follow some advices on reducing the pdf file size - http://www.dopdf.com/forum/topic/keeping-file-size-down
I'm not so sure the statement "if it works on your computer, then the pdf is ok" is necessarily true. Depends on what software is being used to open the PDF, right?
I use a program on my Blackberry called Repligo Reader to open/read PDFs. Been using it for awhile. For some reason, it does not read PDFs created by doPDF. No problem with PDFs (the same documents) created by Adobe Reader, or another pdf creator I was using prior to doPDF. Something is different.