Hi,
I am using it to index my maildir mails. The gmime-sharp 2.6 is so broken, it is completely unusable, so I have changed to use MimeKit.
Please take a look at my fork at https://github.com/baohaojun/beagle if you are still in love with this project.
Also, I have wrote a beagrep which can grep 9G of android source code in 0.3 second. I use a modified version of beagle first to find out which files contained the words I want to search, then I grep only these files. Please take a look at this project at https://github.com/baohaojun/beagrep . I wrote an blog article about beagrep at http://baohaojun.github.io/beagrep.html .