I am sending an email to a coworker using mac osx mail client.He is using a Windows machine with Microsoft Outlook 2013. When he receives the email the text is visible. However when i forward an email to him ( or my other colleagues with macs) he receives the text as an attachment. The same happens if I forward an email from a Windows machine using thunderbird. The text automatically is attached and not visible. How do I fix this and where is the problem really ? Is it in the mail clients that send the email ?
I tried sending (forwarding) mails from a few Mac computers and one Windows machine and the same happens but only with one specific Mac, the problem doesn't appear there.