Send rate limiting is utilized to throttle, or spread out the sending of a sent email campaign. By default our system spreads out the sending of the email campaign per minute. For example, if an email with a 100K recipient list spreads out over 6 hours, that means 278 messages per minute will be sent. If you are on an Enterprise license, you have the option to adjust your own send rate over a 24 hour span. You will find this option in "Finalize" tab when creating a new email campaign.
Note: Deferrals or unsuccessful initial deliveries will put the campaign in the default retry schedule. In addition, if an ESP adds their own throttling, the campaign could extend the time period set in Delivra.