Untested subject lines are a crapshoot. Like many things in life, subject-line performance falls on a bell curve. Some perform exceptionally well. Most are average and some perform relatively poorly.

“Writing a subject line is kind of like throwing a dart,” says Alex Yale, insights director, Alchemy Worx. “Usually, you’ll get one that’s average. Sometimes you’ll get one that performs poorly, and sometimes you’ll get one that performs really well.”

The trick is identifying the top-performing subject lines before the campaign rolls out. But there is no way to predict how any given subject line will perform without testing.

And the timing and length of the test are key.

For example, testing subject lines on the morning of a scheduled campaign generally won’t produce reliable results because the recipients will represent the sliver of the overall audience of people who are active in the morning.

Many email service providers offer automated subject-line testing, but the results come in too fast to be accurate. It can take days for subject-line results to settle down and show the true winner.

But what if there was a way to ensure subject lines are always top performers? Well, there is. It’s called pre-rollout subject-line testing. Done properly, pre-rollout subject-line testing can boost click rates an average of 30%.

The idea behind pre-rollout subject-line testing is creating a landing page three days before the campaign and testing the various subject lines against a subset of the rollout audience.

“If your campaign is scheduled to go out on Wednesday or Thursday, then maybe on Sunday or Monday, you deploy your emails to a small subset, and then you have three days to acquire data and figure out which one is the winner,” says Yale.

The challenging part of pre-rollout testing is it requires having a landing page, offer and any relevant coupons ready for the campaign three days before the rollout occurs.

“It requires some up-front work,” says Yale. “But it’s work that would have to be done anyway, and the results are well worth it.”

Case in point:

Alchemy Worx recently ran six pre-rollout subject-line tests for a home warranty company. The lowest performing winner generated a 15% lift in clicks. The top performer generated a 47% lift. The average lift was 35%.

In each pre-rollout test, the winner was a subject line that, without testing, could have been predicted only by a lucky guess.

For example, one test pitted the following five subject lines against each another:

“ATTN: Prime Time Offer Enclosed,” “You’ve Got Prime Time Savings,” “Claim Your Prime Time Savings in a Few Clicks,” “[First Name], Your Prime Time Sale Offer is Inside,” and “This Is It! Prime Time Savings Await.”

The clear winner was: “ATTN: Prime Time Offer Enclosed.” Counterintuitively, the winner was not the personalized subject line, nor was it either of the subject lines that employed versions of the powerful selling word “you.”

“No one would have predicted that subject line as the clear winner,” says Yale. “But it was, and we were able to roll the campaign out knowing we had the best subject line in play.”

Pre-rollout subject-line testing is an operational-process change that requires assets to be created and approved days in advance.

“In my mind, a 30% lift on average is worth the effort,” Yale says. “And if you can achieve those kinds of results on a constant basis, the immediate payoff is gratifying, but the long-term payoff is a significant lift in all key performance indicators.”