A "small fraction" of Yahoo Mail users couldn't get to their e-mail Thursday, the company said.

The outage affected less than 0.5 percent of users for less than 20 minutes, Yahoo said. "The problem has now been resolved," the company said.

Yahoo Mail has 280 million users worldwide, according to ComScore, so even small outages can affect many people. Yahoo isn't the only company to have recent blemishes on its record: Comcast had an e-mail outage on Saturday, and Google's Gmail went down in February.