Do not resend! Your campaign might have been added to our delivery queue right after a number of larger campaigns and it may have to wait for those campaigns to be delivered first. Head into the Reports section of your account and if your campaign is still listed as Currently Sending, then it will be sent out soon.
We'll send you an email as soon as the last email is sent and you can start viewing your reports on the results. If you re-send the campaign while the current one is waiting to send, your recipients will receive 2 copies of your email.
We're constantly evaluating our delivery server queues and add new mail servers to our cluster from time to time to ensure we get your campaigns sent as quickly as possible.