I have been starting to make hotel and car rental reservations. A number of places do not have secure websites for making reservations and ask to send credit card info via e-mail. Is this the norm in Greece? if I do, I usually send the info in two installments.
Yes, it is the norm for many hotels. Some also ask for bank wire transfers instead of credit card payments. Some now use PayPal. Sending your information in 2 emails instead of one is a good idea. Just be sure they know in advance and have agreed.
Or call them being mindful of the time change.
There really is no gained advantage with sending credit card info in 2 emails. The chance of a hacker reading your email is remote. But there is also nothing wrong with doing so if it makes you feel more secure.
Besides, "secure websites" really aren't that secure. Those are the targets of hackers, not reading billions of emails sent everyday.