Thank you for your post.
I need some additional information before I can help you further.
Which version of Windows are you using? Are you sending via Email client or SMTP? IF Email client, which Email client are you using? Is this done through a script or from the File menu? What fields are being filled out? Are any other applications running?
The crash comes in creating the PDF rather than in sending the email. You may delay the bug by ensuring that your layout does not extend beyond the edge of a single page, but that is only forestalling the inevitable. Large PDFs are still going to crash. There is another thread on this. Search for "PDF Crash" to see another conversation.