One of the spam appliances had an internal failure last night, which caused it to not be able to properly scan email and deliver it. As a result, there were about 54K messages queued up. It is currently going through the queue and delivering those messages.
UPDATE
[2008-01-29 16:11:03 | Venk Seelam]
One of the spam appliances had an internal failure on sunday night, which caused it to not be able to properly scan email and deliver it. As a result, there were about 54k messages queued up. It has finally went through the queue and delivered all the messages and the mail delay has ended.
Resolved as of 2008-01-29 12:36:00