Be careful when greeting across cultures. Many years ago, I was learning German. My prof told me that "Wie gehts?" was replacing the more formal "Wie geht es Ihnen?", especially among close acquaintances. Soon after, I happened to visit my "uncle" (really, a close family friend), who emigrated to the U.S. from Germany as a teen soon after WWII. I greeted him with a jaunty "Wie gehts?", hoping to impress him with my slick German. He was mortified! After growling something in German, he informed me that "Wie gehts?" was a greeting that only very low-class Germans would use, and that using it with one's uncle was insulting. (Ach, those class-conscious Germans!)
My point is, even when you think you know the culture, I would err on the side of formality for a first email. Your greetings can gradually get less formal as you trade correspondence.
Kind regardsis certainly formal but also warm.Cheersis common work-casual andThanksis also a great way to go. – CLockeWork Feb 07 '14 at 09:52thanksorgood luckif appropriate to the content of the email. Here 'Best' heavily used in business here, and thus has a formal connotation.Cheersis casual with a hint of warmth. – virtualxtc Feb 07 '14 at 10:09thanks, but still close withregardsas I often feel the need to convey respect when talking to other scientists, andthankson it's own can come across as presumptuous and terse. – virtualxtc Feb 07 '14 at 21:31Thankswhen my email is asking for something, though dependant on how much and I'm asking for, and from whom, I may useThank youinstead. – CLockeWork Feb 10 '14 at 09:22