Send one million emails per day

Does the software support multiple outgoing email accounts sending at same time? Also what is the realistic number of emails/hour that is will send under average conditions (average desktop). I am looking for software to allow me to email out 1million/24 hours to opt-in lists. Although I can run multiple versions of the same software if necessary.

No, the software currently only supports one outgoing email account, ie, one SMTP server.

The speed of sending out an email largely depends on your server. It is not dependent on the email client software (Broadcast By Email). Usually, commercial email servers control the amount of emails it can receive from email client. Broadcast By Email does have control to slow down sending emails, in order not to flood your email server and your emails being marked as spam. We do not know the exact connection speed you have, but normally, you can send one email a second.

To send 1 million email per day, you need to send about 12 emails per second. So you definitely need multiple email servers and use multiple Broadcast By email software.