Between May 10 and May 13, Microsoft Business Productivity Online Suite (BPOS) suffered a string of cloud outages that caused lengthy cloud e-mail delays for BPOS users. Trouble started around 12:30 p.m., Tuesday, May 10, when the BPOS-S Exchange service experienced an issue with one of the hub components due to malformed e-mail traffic on the service. Microsoft said Exchange features a built-in capability to handle malformed traffic but "encountered an obscure case" where that also didn't work correctly, creating a backlog of e-mail. The issue caused delays of six to nine hours. Then, on May 13, more issues caused e-mail delays, resulting in more than 1.5 million e-mail messages getting stuck and awaiting delivery. Microsoft fixed that issue by 3:04 p.m. and all e-mails were cleared within a few hours. That May stretch was the beginning of a rough month for BPOS, which saw four outages in roughly a month's time.