Eudora 4.x allows remote attackers to bypass the user warning for executable attachments such as .exe, .com, and .bat by using a .lnk file that refers to the attachment, aka "Stealth Attachment."
http://news.cnet.com/news/0-1005-200-1773077.html?tag=st.ne.fd.lthd.1005-200-1773077