CopiaFacts e-mail services are licensed per channel (thread of execution). A thread is a unit of work in the COPIAFACTS server engine. If you have ten licensed e-mail channels, you can send ten e-mails at the same time.
Although the number of channels affects the throughput of your system, increasing the number of channels will not always increase throughput. The throughput is also affected by the following factors:
•The speed of your processor and the number of CPU cores. For a given overall processor power, more cores give less thread-switching overhead. Unlike fax or voice operations, adding CPU power can increase e-mail throughput, provided you are not limited by your internet connection.
•Message size. Sending big attachments takes longer and increases the load on the Internet connection.
•The capacity of your Internet connection. If the pipe is full, increasing the number of channels sending through it will merely slow down the transmission. Your Internet connection is the ultimate limiter of your e-mail throughput: If you want to send 10,000 e-mails per hour, each of 100kB, you will have 1GB of data to send in 3600 seconds. This requires a connection with 2.5Mb/s upload speed before taking into account overheads, MX look-ups, and other factors.
•The quality of your Internet connection. Packet loss causes re-transmission and delays.
•DNS server performance. Before sending each e-mail, COPIAFACTS normally needs to find out the mailserver for the destination using DNS look-up (unless e-mails are being consolidated).
•Disk and network performance on your fileserver on which the COPIA share resides. COPIAFACTS needs to find work by reading FS file queues.
•Your COPIAFACTS configuration. For large-volume e-mail applications we strongly recommend dedicating TOSEND queues for e-mail, and using separate machines (or virtual machines) for e-mail. This avoids an e-mail node having to discard fax FS files which it cannot process.
•Your use of MSMQ. For some bulk e-mail applications, it may be appropriate to use the option to launch e-mail FS file images into a message queue to speed processing. Please contact Copia Support if you think this may help your applications.
•Your typical destination addresses. For many popular mail hosts, such as AOL, Yahoo and Gmail, the destination may see high rates of incoming mail as spam and apply either a block or rate limitation ("do not attempt a resend for ten minutes"). CopiaFacts supports DKIM (Domain Key Identified Mail) which may help to reduce the chance of being identified as spam. See also Appendix O for help with avoiding e-mail block lists.
Because of the number of factors involved, estimating capacity and channel requirements can be complex. Please contact Copia support for advice it you plan to send large volumes of e-mail. For sending only occasional e-mail notifications from your CopiaFacts system, one or two channels is usually adequate.
You can use the CALLMON utility to show statistics of how many e-mails you are sending and the rate of transmission.
