If you assign multiple SMTP servers to send out your messages in "Multi-SMTP-Server delivery mode" or "Mixed delivery mode", Email Marketer can automatically balance the load between these servers. For instance, if you have 1000 messages to be sent and you assign 10 SMTP servers to do the job, then each server will handle about 100 messages. This feature takes the load off of your SMTP servers and speeds up message sending significantly.