An e-mail system is described that includes a mass-mail accelerator (MMA), which is particularly suited for processing mass e-mailings. Instead of being posted to a message transfer agent (MTA), outgoing messages are instead passed to the MMA for carrying out highly parallel e-mail delivery / routing. The MMA employs a plurality of queues, which may either be general or specific. A specific queue is configured to handle only e-mail destined for a particular domain, such as the AOL.com domain; a general queue is configured to handle all other e-mail. Each queue manages a pool of MTA threads. During MMA operation, once a message has been passed to a queue, that queue examines its MTA threads to see if one is ready to accept the message. If an MTA thread is ready, the queue will assign the message to that MTA. The MTA thread proceeds to handle the work of the SMTP exchange between the MMA and the target real-world MTA (e.g., an AOL MTA). While a given MTA thread is waiting for a reply from the real-world (destination) MTA (e.g., the AOL MTA), the MMA can proceed to do other work. In this manner, the bottleneck usually encountered with processing mass e-mailings is removed.