I have tried using a number of plugins to email my 40,000 registered users on my WordPress-powered site, to no avail. I have tried Subscribe2 (seems to send some, but I have no idea how many) as well as a few Newsletter plugins. I either run out of memory trying to add 40K entries to the mail queue, or I error out trying to add 40K emails in the BCC of the email being sent.
Is there anyone out there with a large subscriber-base that has found a successful solution? If so, please share.