The company with the purple logo has some of its email users seeing red. Jeffrey Bonforte, the senior vice president of communication products at Yahoo, apologized for the problems Wednesday on Tumblr.
"The issue has been harder to fix than we originally expected," said Bonforte. "We have dozens of people working around the clock to bring it to a resolution."
Yahoo first acknowledged the mail outage on its Twitter account the afternoon of Dec. 10. Most recently, Yahoo said that the affected servers had been repaired and were now working, though some users may still have problems receiving emails sent during the outage as well as logging in to their accounts.
The company did not immediately respond to ABC News' request for comment, but it is expected to give the latest updates on its help page later today. Yahoo also said that it expects to have all the remaining emails processed and sent later this afternoon.