Google Apps Premier Edition / Postini
Using BBC is not the best practice for sending large groups of recipients, as is using a mail-list service for this task. This practice will most often be screened more critically than regular messages, say with less than 25 CC or BCC recipients. Some mail services will actually restrict inbound messages with a set limit, as this practice is a common spammer tactic. You should also make sure you have a published SPF file in DNS.