I recently upgraded to Office 2016 (365). Everything appeared to work properly, but now when I send attachments via Outlook, most of the recipients cannot either see them or open them. Attachments have all been Excel, Word, PowerPoint and PDFs. When trying to open the attachment the recipient gets the error message stating the file is invalid, has the wrong extension or is corrupted (various wordings depending on whether it is Excel, Word or PPT, but essentially the same message). PDFs either do not show up as attachments or will not open. The attachments have been from files on both my OneDrive and on my desktop. I can open all the files on my desktop, but if I send myself an email with the attachment, it will not open per the error message stated above. I conducted an Office 2016 repair and have reinstalled Office 2016. Same problem continues.
I have spoken with three tech support people at Microsoft with no idea on what was causing the problem. The last and final solution from MS was to revert back to Office 2013, which I did. When I reverted back to 2013 everything worked properly. However, when I forwarded an email to myself originally sent from Outlook 2016, the same file would not open. There have been more than half a dozen recipients using various versions of Windows and Office that have seen this problem from my emails, so I know it is them, not me with the problem.
I am a power user, so I have good computer knowledge. About 3 days before upgrading to Office 2016 I upgraded from Win 7 Pro 64-bit to Win 10. It went absolutely smoothly. No conflicts. All drivers and peripherals working, so I don't think that is the problem.
Is anyone else seeing this?