Mountain Lion users advised to use a different attachment type, or a browser
Users of OS X Mountain Lion may experience issues when attempting to send a message containing an EPS attachment. Apple has a quick workaround for the problem, as disclosed in a newly published support document.The Cupertino giant acknowledges that Mail may stop responding when adding an EPS attachment to a message. You can quit and reopen it to regain control of the app, but you still won’t be able to use the built-in Mail client of OS X Mountain Lion to whisk away your EPS attachment.
Until the issue gets patched, Apple has a workaround: “As a workaround, use a different attachment type, or access your email account through a web browser and attach the file,” says the Mac maker.
An alternate solution is provided (probably the best choice for users who insist on using Mail.app to send their EPS attachment to someone).
The company says you can compress the EPS file to a zip archive and then attach it. In other words, Mail in OS X 10.8 won’t have any problems attaching a .zip file to your message.