Announce list: Gmail never receives confirmation

We’re having trouble with the confirmation email that’s sent when a person signs up for the announce list.

We’ve tried 6 different Gmail addresses, and none have received the email. The message is not in the junk folder. Non-Gmail addresses work fine.

The Dreamhost support person I wrote to was able to receive the message in his Gmail account, and he said that Gmail do not block mail from Dreamhost’s servers.

I don’t think it can have anything to do with the content in the mail, because I’ve tried removing all the text from the message and the subject line and just replacing them with “test” and there’s no change.

I did submit a message to Gmail’s support, but they don’t answer the mail they receive.

Does anyone have any ideas about why this could be happening?