I have over 150,000 emails on my lists and once a month I like to send an email to everyone. However, if I do it with a single e-mail then my website gets slaughtered by all of the traffic arriving at once. Other platforms <cough>MailChimp<cough> offer the ability to send emails in batches to minimize this issue. I'd like to be able to choose how many emails to send and how far apart, for example, I'd like to send 10 emails 30 minutes apart. This way each email would only be 15,000 users and the additional website traffic would be spread over a 5 hour period rather than being concentrated into a single spike of unmanageable activity.