A lot of your marketing emails never get to the recipient. Fact. There's no point in bemoaning the crudity of some of the "email filters" which people have in place; they exist, they work badly, and we just have to get on with it.
However, we can at least do as much as possible to reduce the number which get swallowed up into black holes set up by some work-experience kid in your customer's IT Department. As Editor of Engineeringtalk for over eight years, I probably sent out 15 million (all-requested!) emails to professionals, so this was a subject close to my heart. In 10 Email Pitfalls and 10 Email Power Words on the B2B Lead Blog, the author summarises an article from the MarketingProfs newsletter which gives you ten words to avoid. As these include terms like "Safety" and "Guarantee", they're – unfortunately – rather important in the industrial sector.