Back in January this year I had this exchange with Daniel from Canada:
Daniel: "I'm looking for the email address of the Hertz car rental office at Málaga airport but I can't find it anywhere. Do you know where I can find this information? Thank you."
Mike: "Hello Daniel, I picked up your email yesterday while visiting my grandchildren in London yesterday and so on my way back through the airport last night I walked down the long ramp from arrivals to the Hertz division in the Malaga airport car hire section.
I stood in line to get the information and at the Hertz desk itself I was given the web address of the Hertz car rental department at Málaga airport as www.spagp50.com. I haven't checked it yet but you should be able to find the email address on the site. Best wishes from Marbella, Mike"
Daniel: "Hello Mike, I tried the web address for the Hertz car hire at Málaga airport you sent me but unfortunately it doesn't work. Thank you for your help anyway, I appreciate it."
Mike: "Hello Daniel, I should have tried it myself before I sent it to you. I asked the fellow to repeat it three times. I have just tried it too and it didn't work. Anyway I looked up the central Hertz number in the Spanish Yellow Pages and after getting the run around with recorded voices and extensions I managed to found a live voice and a live operator.
The agent gave me the telephone number of the Hertz desk at Málaga airport as 95 223 30 86 and so I phoned them and the girl there gave me the email address as email@example.com. Obviously the guy behind the desk last night had no idea about email addresses.
Try that and see if you get through to them. Best wishes Mike"
Footnote: I didn't hear back from Daniel but I imagine he managed to make contact with the Hertz desk at the airport. At least I hope so.