I wouldnt do it.

Everyone going to our apartment has to first fill in an advanced Booking Form and sign the terms and conditions.

In return we give them a full Booking Confirmation signed and dated, a full information pack with Health and Safety instructions, a 24 hour emergency contact number and a written Permission Slip stating that they are in the apartment with our full knowledge and consent both in English and Spanish and this is also signed and dated.

If you are going to do it at least do it right.

I have done it with www. eurosol.com and always found them very helpful. They do send you their terms and conditions by email, but payment and contacting them is easy.

We now use them for all our holidays

I would advise anyone to be very careful if they using an external agency or any other 3rd party to manage or arrange their bookings.

It s very difficult IMO if not impossible to argue that doing it this way complies with the current concession under the local laws that allow private owners to rent out their own apartments.

I have used private rentals for a couple of years and so have my family and friends and we have never had a problem. I suppose there are some people who are out to rip you off but that can happen through booking agents and some tour operators. The people that we have all dealt with have been very helpful to our parties and arrange transfers and any other request that we have had. Good luck and just ask lots of questions before you decide to part with your cash.

I have rented from private individuals for about 10 years through email etc and I don't remember ever getting a paper agreement. I'm sure thousands of other holidaymakers do the same without any problems too.
If you are anxious about doing this for the first time may I suggest going through a reputable website such as http://www.holiday-rentals.co.uk or OwnersDirect? Most of the advertisers on these sites are renting their properties regularly, and you may feel you have more back up should anything go wrong. This site is not an agency, so you will still be dealing directly with owners but not paying the middleman, which is all an agency is.
Dealing directly with the owner is cheaper and usually better accomodation than the agencies who let properties which they don't own or use themselves. Usually owners holiday in their properties themselves and therefore maintenance,furnishings etc are paid more attention to. The only apartment I rented which was disappointing was an investment property bought just for letting.
Take the plunge and enjoy!