mail attachment mime types

I have written a form to mail script using the mail()function I decalre the mime type of my binary attachment in a variable like so- $mime_type = "image/gif"; "Content-type:$mime_type; name=\"file name"\r\n"; Want I want to do is have a list of usablemime typesas I cannotalways secondguess what willbesent. Would I have a string such as $mime_type = "image/gif"|"image/jpg"|"mime type3"|"mime type 4"; Thanks in advance