Yikes well.. I know one by one should work.. and I know in Entourage I can select all my contacts and throw them on the desktop and I can then import them somewhere.. so Im sure you can do that will mail.. just select them all and throw them into a folder. Either it will create a whole bunch of files or it will create one gigantic file that will have all the contacts within it... Then just take that file or group of files and drag them into your new mail app...
I have spent half a day RE-Typing addresses and e-mail addresses into Address Book in Panther. All of my data is in OutLook Express on a Mac 9500. My new machine is a G5. There has got to be a better way.
When I drag the individual addresses from OutLook Express to the desk top it makes a file that only shows the name and e-mail address. I can drag an address to the body of an e-mail, send it to the new machine and I get the name and e-mail address. Nothing that I have been able to do has made a vCard file.
In your new computer, install Outlook or Entourage, and import your addresses the old way. It must be on your new computer.
In your harddrive (in Panther) /Library/scripts/mailscripts is a script called ImportAddresses.scpt Run this script and it will convert the addresses for you and place them in your address book. It took all of 3 minutes.