Something to do with EML file.
This is an example of what it does but this is for Outlook express so not sure about Talk talk.
You need that file usually to open attachments.
If talk talk is your defauld e-mail provider it should have this file.
If you use another e-mail provider it will probably be on that and may have to be transferred but not sure how you would do it.
I am sure someone will be able to give you further advice.
All I know is that you need the EML File.