A recent Apple Support Note warns users that Mac Mail in OS X Mountain Lion (10.8) will "stop responding" when users try to add an EPS (Encapsulated Postscript) file as an attachment. There is a workaround.
As a workaround, use a different attachment type, or access your email account through a web browser and attach the file.
Alternatively, first compress the EPS file and then attach the compressed (.zip) version of that file to the Mail message. To compress it, select the .eps file in the Finder and then choose File > Compress.
This talk of attachments reminds me of ChungaSoft's ForgetMeNot, an interesting Mail plug-in that scans your e-mail before you send it and checks if you've forgotten an attachment. The company is Fabian Jäger and his brother, Paascal. The software was released last spring and costs $5.95.
Probably everybody had this feeling before: You just clicked on "Send" in your favorite email client and immediately after realized that you mentioned an attachment iny our email text, but forgot about attaching the described file to the email. What do you do now? You send another email with the files attached and something like: "Here are the attachments - finally." Forget about these embarrassing emails from now: Install ForgetMeNot and never forget about attaching files again!
If a keyword shows up in the scan and there's an attachment, then the message will be sent; otherwise, ForgetMeNot will ask you if there should be one. This magic is done through a keyword dictionary, which comes knowing many common keywords such as the permutations of "attach" and users will (must) add others. There's a field to add custom keywords in the ForgetMeNot preference in Mail prefs.