PDFs downloaded to my computer won't open when sent via email

I've been trying to send pdfs from Quickbooks Online. At first I tried simply sending it from Quickbooks, but a number of people were not able to open them. For months I was uploading them to Acrobat, downloading them to my computer and sending them that way. That was working for a while, but for some reason stopped. Now it seems some people can open them, but not everyone. Is this a problem on my end? They are getting a message that the file is corrupted and cannot be opened.