Beware of email with Subject Order Number or Purchase order number with an html or pdf attachment: Locky Ransomware Example

The emails look like this:

The attachment is either a pdf or an html file.  These should be trashed and reported to your eMail provider.  A description of what is probably in these files can be found at http://www.bleepingcomputer.com/news/security/the-locky-ransomware-encrypts-local-files-and-unmapped-network-shares/.  This can be very bad ransomware, locking your computer until you pay a large "fee;"  I'm talking $3000; even from friends or your bank.  Don't click on attachments.  Those days are gone.  GONE! 

Personally, wherever I have a financial institution or friend that sends an attachment, I let them know I won't open it.  If it is an institution, I call their security and give them an earful.  My experience is that they quickly change their procedures and the result you should ask for is that they ask you to go to their website and look at their messages.  No more PDFs sent to you.  If it is a friend, have them permit you to a service like Google Drive, Dropbox, or Microsoft Livedrive to look at the document.