I shall be interested to see what further methyl has to say on this matter.
In the meantime I am thinking that your friend has picked-up a 'nasty' and in addition to running a full Anti Virus Scan should also do a Scan with Malwarebytes. You should also do likewise in case the unopened mail did leave something behind without any indication to you.
The free edition of Malwarebytes can be downloaded and run from the following official site :-
http://www.malwarebytes.org/
Make sure that you Do Not accept a trial of the Premium Edition or anything else which is on offer.
Hans.