The move set off a social-media debate over how political companies should be and what it means for their business and employees. Some Expensify customers said online that they would stop using the company’s expense-reporting tools, while others said they would start using its software because of the email.

Pressured by some employees and consumers, more business leaders have spoken up on political issues, such as gun control and immigration policy, in recent years. But few have gone to the lengths of Expensify, directly urging its customers to pick one political candidate over another. While many CEOs say political stances on nonbusiness matters risk alienating customers and parts of their workforces, Expensify’s CEO and founder David Barrett says that saying nothing is a corporate statement in itself.

“There’s this idea that, as a business owner, you’re supposed to be neutral,” he said in an interview. “We need more people to get into the fray, and say, ‘I do not like the status quo.’ ”

Mr. Barrett said he and others inside the 130-employee company spent about a week debating the content of the note, and whether to send it. He also said it was a business issue: “Expensify depends on a functioning society and economy; not many expense reports get filed during a civil war,” he wrote in the email.

Reaction online was almost immediate.

One technology executive wrote on Twitter that “I can’t remember ever seeing anything even remotely close to it.” Another Expensify user called it “gross negligence in sending out a politically charged email” to the company’s customers.

Mr. Barrett, 44 years old, says the risk in losing customers is real.

“Of course we’re worried about that,” he said. But it is also possible the email, and the publicity surrounding it, could draw more attention and customers to the company, he said. It is a calculation a handful of other brands have made in their own support of more political, often liberal, causes. Spice company Penzeys Ltd., run by CEO Bill Penzey, spent hundreds of thousands of dollars last year on Trump impeachment ads, while

Unilever

PLC’s Ben & Jerry’s led a campaign to help restore voting rights to Florida felons in 2018.

“Customers want to work with brands that share their values, and I think that the value of promoting democracy is a pretty universal one,” Mr. Barrett said.

Mr. Barrett first proposed the idea for the email in a company Slack room where employees write to identify problems and possible solutions. He ultimately shared a draft with all employees, allowing them to suggest changes and revisions. Not everyone agreed with it, but “everybody had a voice in it,” he said. A team of about 20 senior employees then voted on whether to send the email; more than two thirds agreed to do so.

Over the past few years, many business leaders have taken more public positions on social issues such as racism and climate change, but have stopped short of directly criticizing President Trump. “There’s just huge sensitivity about being perceived to take sides in what has become such a fractious national political standoff,” says Kathryn Wylde, chief executive of the business group Partnership for New York City, whose members include large employers.

The chief executive of cryptocurrency firm Coinbase Inc. last month said the company wouldn’t allow workplace debate of political causes or candidates unrelated to its business. It offered severance packages to any employee who no longer wanted to work at such a company.

Even in the remote era, though, political divisions are beginning to seep into workplaces. In a recent survey conducted by the Society for Human Resource Management, 44% of HR executives said political volatility had intensified at work. In the 2016 election, only 26% of respondents said such tensions had increased compared with prior elections.

Expensify’s Mr. Barrett said he didn’t worry his stance would alienate current or future employees who opposed his views. “You can only be an inclusive environment if people are free to disagree, but that means doing things that people might disagree with,” he says. “If the rule is you can’t do anything unless everyone agrees, that’s not very inclusive.”