It is not clear whether Hestia, run by Kurt Wolf, plans to nominate director candidates for election to the company's nine-member board.
A Pitney Bowes spokesperson was not immediately available for comment.
Pitney Bowes, which is headquartered in Stamford, Connecticut, is valued at $628 million.
Wolf believes Pitney Bowes should focus on cash-generating segments like Presort Services, its mail aggregation business, and SendTech Solutions, its postage meter business.
Securities filings show that Permit Capital, LLC and Miller Value Partners LP, which were also investors in GameStop alongside Hestia, are also invested in Pitney Bowes.