With mobile overtaking the desktop for email open rates, I was doing some research this afternoon on the viewable length of subject lines on a mobile device. Subject lines are typically more important than the email content itself when it comes to the behavior of the reader and whether or not they're going to open the email.
Now that most email is open on a mobile device, the number of characters you have on an iPhone, Android, Windows or Blackberry device is incredibly short… ranging between just 33 and 44 characters. Our subject here… Mobile Email Subject Line Displays comes in at just 34 characters. That's not a lot of room to raise the curiosity of our reader and get them to open – quite a challenge for email marketers.
This infographic from Mass Transmit details the research on email subject line displays on mobile devices.