If you created an account, you probably never received the activation link. It should now work as expected. You'll have to recreate your user, though. Sorry.

Short explanation: for some reason when Drupal sends an email using the PHP mail() function, the From address in the enveloppe of the mail was set by postfix to the www user with a localdomain domain name, so the MTA of my iSP bounced them. Adding a fifth "-r www@i2bp.com" parameter to the mail() call fixed that.