Closes to Unsolicited Submissions has announced that, effective January 7, 2016, they will no longer accept unsolicited short fiction submissions:

We’ve found some of our favorite, most innovative, and most surprising stories through slush. However, in recent years we’ve found that more and more of our stories have been coming to us from different sources. As more of our stories are being brought in by consulting editors, fewer slots on our schedule can be filled by submitted stories…. Our dedicated editors and readers will read through and respond to everything that is submitted up to that point, but we do not plan to reopen in the foreseeable future.