Washington (CNN)A lot changes in seven years. Just ask Hillary Clinton's campaign.
When Clinton launched her campaign in April, her staff -- armed with the list of 2.5 million email addresses from the former secretary of state's failed 2008 campaign -- hit send on their first 2016 message.
The realization they received shortly after that stunned them: Less than 100,000 of Clinton's 2008 emails addresses were still active and usable.
Teddy Goff, Clinton's top digital strategist, had thought going into the campaign that around 1 million of the 2008 emails would still be active. But the realization that only a fraction of those emails still worked was a slightly sour point on an otherwise "successful" day for the campaign, he said.
"It wasn't as if we all kind of retreated into a bunker to drown our sorrows or anything like that," Goff said Wednesday. "In the midst of that day, discovering that we were really rebuilding a list virtually from scratch, it was a realization that there was going to be a tough road ahead."
To respond to this problem, Goff and the campaign launched what they dubbed The "Hillbuilder Project," an internal campaign push that urged all staff members to think about and act on how they could build the campaign's email list. Goff called building the email list the "the single highest priority, for now" on the tech and digital side of the campaign.
Signs were put up around the Brooklyn headquarters that read, "What are you doing to grow the list today?" Organizers in New Hampshire, Iowa and other states were urged to get emails from everyone they spoke with and add them to the database. And at an all staff meeting on June 12, the day before Clinton's first big rally in New York, campaign manager Robby Mook included list building as one of the campaign's top three priorities for the summer.
"This is not just a digital thing," Goff said, "this is a campaign priority."
The campaign's goal, Goff added, was to provide "relevant content" and allow people to connect with the campaign so that they can "provide an experience that people are going to like."
Part of that is content that taps into the news of the day. Most campaigns do this: A big news event happens, so the team blasts out an email and post social media content that looks to build their list.
When the Supreme Court decided to make same sex marriage legal in all 50 state, Clinton's campaign sent an email -- subject line: "Full Hearts" -- that asked people to "celebrate history" by adding their name to a list. The campaign made similar pitches on Twitter and Facebook, including a video titled "Equal" about gay marriage that received more than 3 million views on Facebook.
The goal of these emails and lists is to make people who support Clinton feel like they are missing out by not being on the list, campaign aides have said about their digital strategy.
Another way Clinton's campaign grew the list was by swapping with other groups, including Ready for Hillary, the super PAC that spent 2013 and 2014 urging Clinton to run. While the super PAC had a number of priorities, including engaging grassroots organizers who wanted to support Clinton, Ready for Hillary's top aides long said that their main focus was building a sizable list of current and engaged Clinton devotees.
The campaign gained access to the Ready for Hillary email list in May and started to use it for fundraising and other pitches shortly thereafter. But Goff said Wednesday that while the list was helpful, it couldn't make up for name generated by the actual campaign.
"I think all of us are very appreciative of Ready for Hillary and what they did," Goff said. "It has been valuable, but at the same time, it is incumbent on us to build our own community."
He added, "The fact of the matter is an email address that an entity acquired on its own either by a petition or by an online ad is always going to be a little bit more active and engaged than an email address that is acquired by the way of a swap."
The biggest reason email lists matter is fundraising. Previous presidential campaigns, including President Barack Obama's 2008 and 2012 campaigns, have raised huge sums of money through email and online fundraising. Goff was the digital director of President Obama's 2012 reelection bid.
Like other campaigns, Clinton's operation will release their first FEC report on Wednesday. Campaign aides have already previewed that they raised over $45 million in primary money during their first quarter, part of that through digital fundraising. The FEC report, however, will not itemize what money came on line, however, and what came through other venues.
Campaign aides also would not disclose the current size of their list or goals they have for the list building project. Goff did say, however, that the campaign is "more concerned with the output of the list than with the size of the list."
"We would rather have a couple million really good email addresses by election day," he said, "than 15 million really bad ones."