Topic Last Modified: 2007-01-24

You can limit the number of messages sent in a single connection. Limiting the number of messages per connection provides a method to improve system performance by enabling multiple connections to deliver messages to a remote domain. When the set limit is reached, a new connection is automatically opened and the transmission continues until all messages are delivered.

For example, if you typically send many messages to certain remote domains, you could set the Limit number of messages per connection to value to a relatively small number, such as 20. As a result, when sending 100 messages in one session, the SMTP service immediately opens a new connection after the first 20 messages are sent, another after the next 20 messages are sent, and so on. In this case, there could be up to five simultaneous connections delivering queued messages to one destination. Message delivery would be faster, because fewer messages are delivered at the same time, instead of in one long stream over one connection.

To determine a value for the limit, review the Messages Sent/sec performance counter for the SMTP Server object in System Monitor. The Limit number of messages per connection to value should be less than the value indicated by the performance counter. If the counter indicates a value of 30, and you set your maximum connections to 50, no simultaneous connection would be opened because the server wouldn't exceed 30 messages per second. It would work as if the messages were sent in one long stream over one connection. This setting affects outgoing messages only. You can use it to increase your server output speed. However, it does not affect the rate that other servers process incoming messages.

Procedure