emix files size

My white 13" Macbook running Mac OS 10.6.8 has a 250 gig hard drive. I began getting warnings that my startup drive was full. Going into the files I found that the User/User/Mauilboxes/Recovered Messages folder had 105.7 gigs of emix files. Each file was 131.6 MBs and almost all the files havebeen created during the past 3 months. I copied these files to an external drive, then deleted the 105.7 gigs of emix files on the hard drive.

So, What is an emix file (I use Gmail)? Why are they so large? Are they essential? Why are they being created at a rapid rate?

Any answers would be extremely helpful.

Thanks,

Charles