Adestra recently
published their 2013 Subject Line Analysis Report that presents the key findings of their latest research - a survey of over 2.2 billion emails, from over 90,000 campaigns, to identify keyword trends in subject lines (covering the words and phrases that get recipients to open emails OR are overused and ineffective.)

The research was split into six sectors: B2B publishing, B2C Publishing, B2B Events, B2C Events, Charities & Not for Profit and Retail & Ecommerce.

According to Parry Malm, Account Director at Adestra:

"Subject line strategy should be seen as
a series of branding tools over a period of time, not just one-offs to drive
short term response. With usability firmly in mind, there are key words and
phrases that statistically help drive response in your sector, try them and
test them – constant testing is vital to success."

Obviously, we agree with him!

Here are the key
findings of their research:

• Email communication generally is trending
  towards a better user experience. 
  Brands
  having a “Sale” will drive response by simple saying so (+23.2% open rate,
  +60.7% click rate); brands with something “New” must talk about it (+17.2%,
  +38.2%);  and new “Video” content must be
  promoted (+18.5%, 64.8%).
   
• With the growth in popular content
  aggregators, many people don’t bother to sign up for a newsletter anymore.
  While the word ‘newsletter’ shows a marginal effect on open rates (+0.7%), but
  a strong negative effect on click rates (-18.7%.), ‘Alert’ performs much better
  (+38.1% opens and +61.8% clicks). It’s a great action word, creating urgency
  among reader and gives the impression that the news is breaking, and cannot be
  missed.
   
• It looks as though one of the big trends
  this year, Content Marketing, has over-saturated customers, both B2B and B2C,
  with too much information.  For example,
  “Report” (-23.7%, -54.8%,) “Learn” (-35.5%, -60.8%,) and “Book” (-4.6%, -25.4%)
  are trending down.  Email marketers
  clearly need to focus on differentiating their offering, as delivering content
  marketing is becoming a competitive area.
   
• Creating an expectation to receive
  scheduled messages works well as customers get into the habit of reading them.
  Communications that are sent out “Daily” (+27.8%, +100.3%) and “Weekly”
  (+27.1%, +50.6%) perform strongly. Conversely, “Monthly” (-26.6%, -37.0%) is
  probably too infrequent, losing the top-of-mind position that brands may have
  spent years working on.
   
• Obviously, people like to save money and
  everyone loves getting a good deal. 
  For
  example, simple things like offering “Free Delivery” (+50.7%, +135.4%), or
  specifying a percentage off in the subject line (+10.5%, +27.4%.) seem to work
  a treat.

To get the full picture, download
the full report from the Adestra website.