I've had a Gmail account for a few days now. To play around with it, I thought I'd just load a bunch of emails into it and check out the search and filter functions. Hacked together a little Python script that dumps my archived mail via SMTP into my mail server, which then gradually passes it on to Google. The script ran smoothly. 1305 emails were successfully sent to Google without any error messages (it's only the 1998 archive, which is why there are so few).
Only 640 arrived. Where's the rest? My server sent all the emails to two servers. gsmtp171 and gsmtp57. The first got 556 emails, the second 749. No error messages for these 1305 emails. But I'm missing a large chunk. And the numbers don't add up to either of the two mail servers - so it wasn't a single server either. All emails come from one mail system - so they're syntactically correct, after all they made it to my mailbox. Besides, syntactic rejections should show up accordingly - if attachments were executable, the email would be rejected directly on the mail server (I had 4 of those).
Strange. Somehow this doesn't really give me much hope that Google built something really good here...