Though the email industry has long since set the best practice for subject line length somewhere between 35 and 70 characters, today's Twitter-ized world shows a landscape shifting toward shorter subject lines. In fact, a recent Informz study found that subject lines with just 10 characters or fewer resulted in the highest open rates.
A scroll through my inbox validates that this shift is well underway. I suspect that the past success of short subject lines has been due largely to their novelty: when sifting through an inbox full of 45-character subject lines, the occasional 12-character quip stands out. However, if the current trend of short subject lines continues, it could be the longer line that pulls the eye.
This is a trend that we'll continue to watch, but it's most important to keep in mind that, regardless of the length, the copy should be compelling. Even short subject line needs to tell enough of a story to entice the click.
Here are a few that do the trick:
UrbanOutfitters.com's "Flat-Out Awesome" (March 25)
Piperlime's "What's your sandal obsession?" (April 14)
Thrillist's "SF: The Future Is Almost Here" (April 17)