You'll have to get a phone number of a local ISP in spain, then get a username/password should be easy enough. Then configure a dialup with the above details from your network/dialup connections.
Then you'll need a phone line which the hotel might not be able to provide you and if they do will probably charge you extra for using.
Might be worth your while getting a USB wireless key which can be got for as little as 30e if you shop around. Then access your mail via a wireless hotspot.
Alternatively, most hotels do have an internet access point in the lobby, these are usually not as cheap as youd get in the local internet cafe (1 or 2e per hour) so Id try there first.
sorry, post crossed with CM.