Enter the Google Email Uploader for Mac. It's a simple tool allowing you to upload your old mail to your Google Apps account. That's it! Apple Mail, Eudora and Thunderbird all seem to be supported, but note there are some real limits if you have a ton of email. Here's what Google says to keep in mind:
- Start small. Due to server upload rate limits, the uploader is fast for up to 500 messages, and slow thereafter (1 message per second.) Pick a small subset of your mailboxes when first trying out the uploader.
- Be patient. Even after uploading completes, the server requires a while to process uploads.
- Do assign a custom label (this is checked by default.) This lets you effectively "undo" the uploads later by deleting all messages with the label. Deleting the label itself will not delete the mail.
- If you have many mailboxes in your archives, creating labels for each mailbox probably is not a good idea, as this could create far too many labels.