Study after study indicates that shorter messages increase open rates. For example, the Informz 2013 Association Email Marketing Benchmark Report indicates that subject lines with fewer than 10 characters had the highest open rate (51 percent). If that seems a bit too concise, try to limit your character count to 40. The longer a message sits unopened, the more likely it is that the recipient will delete it. Add a deadline (“Receive 30% off until June 1”) to encourage people to open the message immediately.
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