At about 6 a.m. one of the mail servers, responsible for about 7 percent of AOL member's mail, malfunctioned, AOL spokeswoman Tricia Primrose said.
By 3:30 p.m., mail was restored to about one fifth of those members, or 100,000 people. Primrose expected the remainder of members to be with email by tomorrow morning.
Meanwhile, members were told that they could send and receive mail by creating new screen names. Unlike Microsoft Network, which assigns email servers alphabetically, AOL assigns servers to names on a rotating basis. That means that, while one screen name may be affected by an outage, it is quite likely that another won't, Primrose explained.
While this problem is not the worst outage by any stretch of the imagination, it comes on top of two other mini-blackouts in the last 1-1/2 weeks.
Last week, an outage affected 150,000 of AOL's 8 million-plus subscribers. Then on Wednesday, AOL suffered its second mini-outage when the system was down for four hours instead of the scheduled two, affecting 20,000 people. AOL took down its mail servers to do a hardware upgrade between 1 a.m. and 3 a.m., but problems kept it offline until 5 a.m.
But many others experienced delays all day because of the brief outage. While the system is down, AOL continues collecting the mail but doesn't resume delivery until it comes back up.
Because so many pieces of email flow through AOL's system every day--some 14 million, according to senior vice president David Gang--even a brief outage can cause a major traffic jam. Traffic generally takes several hours to clear, Gang said, likening the backup to an airport suffering flight delays because of bad weather.