I think that they merely want to open a correspondence, and the nitty gritty comes later, when they are in your address book.

I have had several emails purporting to come from a bank, three different banks in fact, including my own. They say something like warning me that they are removing large sums on my credit card, or asking me why my account is in arrears. If I was daft enough to 'reply' to them then there would be an entry in my address book seemingly from that bank, and who knows where that could lead.

I reported all the contacts to the banks concerned, but only my own bank was interested enough to answer me.