How to Import All Your Archive Email Into Gmail (Zolis Blog)
There are several „gmail-loader“? tools on the Net, but some simply don“t work, others change the original sender information to the email account they use for the transfer „ pretty bad, IMHO. My simple solution a year ago was using Thunderbird with a redirect extension. You can read the steps to achieve this here. Even this solution wasn’t flawless: gmail listed all historical mail with the date of the transfer – the original date was sill preserved and searchable, you just got the list display messed up. This still appears to be the biggest hurdle users face according to this new discussion on Lifehacker.