Recipients are unable to open my attachments.

Hi all,

First time posting so please excuse any misused terminology and the like. I'm having trouble with Mac Mail. I use iCloud mail for my service and I have my iCloud account connected to "Mail" on my iMac. I also have a Hotmail account connected to Mail that I occasionally use.

I recently tried to send a PDF to a Windows user using my iCloud account but they were unable to open the attachment. They could view the message fine and the attachment showed up but they were getting an error when they tried to open it. They also tried to save the attachment to their computer and then open it with no luck. When I took a look at the sent e-mail I was also unable to open the PDF. I was getting an error that read:

"Adobe Reader could not open 'Order Receipt.pdf' because it is either not a supported file type or because the file has been damaged (for example, it was sent as an e-mail attachment and wasn't correctly decoded)."

So I tried again with another file type, this time it was a tiff image with similar issues. Still unable to open the file getting a different error message. I then tried using my Hotmail address as the sending e-mail account, still with no luck. I then was forced to use the Hotmail web site to send the mail and that worked fine, much to my chagrin. I then tried to send it via the web based version of iCloud which didn't seem to work from my end at first, I was unable to open the file by clicking on it, still receiving the same error message mentioned above but when I saved it to my downloads folder I was able to open it up clicking on the file from my downloads stack on the dock. Once it opened up this way I was also able to open it up by clicking on the file in the e-mail.

Upon further investigation, I noticed I was unable to open any attachments to an e-mail as soon as I attached them. When I attach a file by clicking and dragging the file into the e-mail, the icon shows up in the mail, which is strange because normally the attachments show up embedded in the e-mail, but when I click on them I get the error message and the file size for the attachment is 0KB. If I try to attach something using the paperclip icon at the top of the mail message a window opens up where I can select the file but when I select it and click "Choose File" the file selection window closes but nothing seems to have attached to the e-mail.

I've been researching this for a few days now and I've tried rebuilding my mailbox, to no avail.

Sorry if this is a little wordy but from what I've seen in forums, the more information you give on what you've done, the better.

Any clue what's going on?

Thanks in advance!