Email marketer Adestra recently issued a report based on the analysis of the subject lines from 2.2 billion emails to determine which keywords work best to boost email open rates.

Having a strong subject line is key to getting your emails open and read, and the Adestra study showed that consumers rate the subject line as one of their top reasons for opening or trashing an email. 

The report broke out email campaigns by B2B and B2C. Here are the best and worst keywords for B2B (note: the first entry on the chart denotes subject lines that use pipes – which are vertical lines -- to divide multiple subjects):

Here are the best and worst keywords for B2C (the 3rd entry on the chart denotes subjects that are separated by commas):

If your email open rates are declining over time, maybe it’s time for you to reexamine whether your subject lines are turning your prospects off.