BBC Learning English site:Mark's Email Mistake

Today i should make a choice between five listen and gramatical class of bbc site and make a resume.

The class is about Mark that sent a mail to his colleague ally,but,ally havent receive the email ,Mark think that is weird,he is sure that sent the email,but he did mistake.

I think that is an interesting form of learn english,with talks that we can hear.The other class are longer but have the text like support.