the body of mail security issues

what are the security issues about mail.body? i want to know when i want to send an email with a form using php, except the email address that we have to validate that, is there any other security issue about sending emails?

for example, which characters can't be used in the body? 开发者_Python百科what about the header or subject? is there any problem with using new line in the body? is a black list applicable here? also, is it possible that with using some tags like <script> in the body, sending email be failed?

all papers that i have read, only say about validating email address and not more!

im researching about security and i want to know all issues about email security in PHP.

Plain text is basically safe. HTML or (shudder) Flash or PDF has the inherent security problems of those formats. In theory, all mail should be 7bit, but MIME changed that so that internaltional information can be handled. The Wikipedia MIME article is probably a good place to start. http://en.wikipedia.org/wiki/MIME