Strange question from Spanish Estate Agent

I am selling an apartment in Spain and my estate agent emailed me a number of queries, one of which was looking for details on the;

"Existing mortgage (amount and bank) this is just because for the clients will be much easier to take an existing mortgage rather than opening a new one."

Isn't this odd? Why on earth would i give this information to a potential buyer?

Well no, not necessarily - in many European countries it is common practice for the new buyer to just take over the existing mortgage rather than apply for a new one and of course it is cheaper as well because there is less paper work. Perhaps it is the same in Spain...