A trigger can also be a passive customer behavior, such as not opening your last few emails, not logging in to use your service for a while, or downloading a product without downloading the tutorial or an important related resource. These types of drip campaigns can help re-engage customers who were moving through the customer lifecycle but have somehow gotten “stuck.”
When it comes to deciding how to craft that perfect subject line, there appears to be really only one area to avoid: the subject line of 60 to 70 characters. Marketers refer to this as the “dead zone” of subject length. According to research by Adestra, which tracked over 900 million emails for its report, there is no increase in either open rate or clickthroughs at this 60-to-70 character length of subject line.