If I initiate contact I always keep my first email extremely formal and polite. You never really know how the other person interprets emails (they could be a to

If I initiate contact I always keep my first email extremely formal and polite. You never really know how the other person interprets emails (they could be a total snob for all you know) so it's better to play it safe. If they respond in a more "casual" way, then I write back in a tone that matches theirs. If I am writing to apologize about something, I try to write it in a more personable manner so that I can connect with them on a personal level. This generally diffuses any tension and makes people more sympathetic (at the cost of making you look less professional.. but something that's just worth it)