Issue with Mac Outlook 2011 sending JPG attachment

Hello

I am using Mac Outlook 2011 to send out emails to my clients.

I noticed that when i attach JPG or JPEG the person receives the email with attachment to it, here is what happens when viewed on phone compared to computer.

When they open the email in iphone they see the attachment but cannot open it, the file is empty.

When they open the email in computer they see 2 attachments same file name 1 is empty and 1 is proper.

This happens only when the email is send via Mac Outlook 2011.

Now when I use my webmail instead Mac Outlook 2011 things works fine and no issues.

This proves that issue is with Mac Outlook 2011.

Any idea what is the issue and how to fix this problem.

Thanks

DP