AIX

( echo "to: trail@somewhere.com"
  echo "from: s64110@elsewhere.com"
  echo "subject: sending file.jpg"
  echo "mime-version: 1.0"
  echo "content-type: multipart/related; boundary=xxxRANDOMSTRINGxxx"
  echo
  echo "--xxxRANDOMSTRINGxxx"
  echo "content-type: text/plain"
  echo
  echo "Body of the message goes here"
  echo "Here is file.jpg for your viewing pleasure"
  echo
  echo "--xxxRANDOMSTRINGxxx"
  echo "content-type: image/gif; name=file.jpg"
  echo "content-transfer-encoding: base64"
  echo
  openssl base64 < /tmp/file.jpg ) | sendmail -t -i