Klaviyo, a Boston-based email marketing automation startup, has hired a former ClassPass COO as the company’s second C-level executive.

Steve Wietrecki, who served as ClassPass’ interim COO from 2015 to 2016, is taking on Klaviyo’s newly created role of chief revenue officer, BostInno has exclusively learned. The company is expected to make a formal announcement on Wednesday.

Klaviyo’s second C-level hire comes after the company tripled annual revenue for the last two years and reached more than 3,500 paying customers earlier this year. Until recently, the company had been mostly quiet since it was founded in 2012 by former Performable employees Andrew Bialecki and Ed Hallen. The company didn’t even disclose its $7 million Series A funding round from former Accomplice partner Jon Karlen until BostInno reported on it in August.

In an interview with BostInno, Wietrecki said the company hired him to build on Klaviyo’s current momentum because of his previous experience working with growth-stage companies. He said Klaviyo doubled its annual run rate this year and now has more than 5,500 paying customers, with more aggressive sales goals for next year. Wietrecki declined to get specific on the company’s revenue but said it’s in the tens of millions.

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“It was quite similar to my experience with ClassPass in New York,” Wietrecki said. “Same kind of growth profile.”

Wietrecki said Klaviyo plans to further expand the company’s leadership team with more C-level roles in the near future. The company is also planning to expand into new markets and broaden its product line, but Wietrecki declined to go into more detail.

Beyond his time at ClassPass, Wietrecki also served as CFO and COO at Rocana, a Boston-based company that was acquired by a West Coast competitor in October; and CFO at NutraClick and Backupify, the latter of which was acquired in 2014.

“Steve brings a rare combination of skills to the table that line up perfectly with the type of company we’re building,” Bialecki, Klaviyo’s CEO, said in a statement. “He’s served as both an operational strategist to startups and a growth-minded executive at public companies. That background will be incredibly helpful as we enter the next stage at Klaviyo.”