http://blog.cloudera.com/blog/2013/09/email-indexing-using-cloudera-search/
http://blog.cloudera.com/blog/2013/11/email-indexing-using-cloudera-search-and-hbase/
http://blog.cloudera.com/blog/2011/09/hadoop-for-archiving-email/
http://blog.cloudera.com/blog/2012/01/hadoop-for-archiving-email-part-2/
http://www.quora.com/Is-HBase-appropriate-for-indexed-blob-storage-in-HDFS
http://www.lilyproject.org/lily/index.html
http://igalia-metamail.herokuapp.com/
http://www.cs.cmu.edu/~enron/
http://2013.nosql-matters.org/cgn/wp-content/uploads/2013/05/HBase-Schema-Design-NoSQL-Matters-April-2013.pdf