Well, after much reading of several blogs, forums and whatnots, I have finally found an easy way to import my many email folders containing my many emails successfully into Evolution from Thunderbird, so I thought I would share.
I am not giving up on Thunderbird, just trying Evolution because I need a good calendar and contact client all-in-one. Hopefully Evolution will work out. I miss you already Thunderbird.
It is pretty easy and all you need is to install the "MBOXIMPORT" extension into Thunderbird. It is, as the tagline suggests, "...an extension that adds a submenu to import/export the mbox files in Thunderbird. Now it can also import the eml files."
Get it here...
...and install into Thunderbird.
.Mbox format is what you want to import into Evolution. To start, select either all or an individual mailbox folder in Thunderbird and export by right clicking on it and selecting "Import/Export" (the new extension), the rest is self-explanatory, just save the exported file.
Once you have saved all the folders/files into the Mbox format, just go into Evolution and select "Import" and follow the wizard using "a single file import" and select your xxxx.mbox file and then select which folder in Evolution you want to import into. Easy!
For importing the address book from Thunderbird to Evolution, use T-birds address book export function and save the address book as a .csv file. Be careful here, not all fields get exported/imported, especially the notes fields. Also, any entry with special characters tends not to transfer over like for example, Mom & Dad. The "&" will cause havoc and prevent it from exporting, from what I gather. Double check all your address entries after transferring.
I hope this helps someone.