In a recent Return Path survey, nearly 79% of consumers admitted that they have hit the "spam" or "junk" email button to get rid of email they don't want. And nearly 37% do it as a way to unsubscribe from things they had asked to receive.
This is not surprising, perhaps, when considering that most consumers get at least 100 emails a week (with 35% getting more than 500) - half of which tends to be commercial. Making your email good enough to avoid the consumer "spam" reflex needs to be a key goal of your marketing department if you want to increase both your delivery and response rates.
Source: Return Path