Once you establish a usage profile, compare it to sample pre-defined user bases that are described in this section. A user base is made up of the types of messaging operations that your users will perform along with a range of message sizes that your users will send and receive. Messaging users fall into one of five user bases:
The sample user bases described in this section broadly generalize user behavior. Your particular usage profile might not exactly match the user bases. You will be able to adjust these differences when you run your load simulator (as described in Using a Messaging Server Load Simulator).
A lightweight POP user base typically consists of residential dial-up users with simple messaging requirements. Each concurrent client connection sends approximately four messages per hour. These users read and delete all of their messages within a single login session. In addition, these users compose and send few messages of their own with just single recipients. Approximately 80 percent of messages are 5 Kbytes or smaller in size, and about 20 percent of messages are 10 Kbytes or larger.
A heavyweight POP user base typically consists of premium broadband users or small business accounts with more sophisticated messaging requirements than the lightweight POP user base. This group uses cable modem or DSL to access its service provider. Each concurrent client connection sends approximately six messages per hour. Messages average about two recipients per message. Sixty-five percent of messages are 5 Kbytes or smaller in size. Thirty percent of messages in this user base are between 5-10 Kbytes. Five percent of messages are larger than 1 Mbyte. Of these users, 85 percent delete all of their messages after reading them. However, 15 percent of users leave messages on the server through several logins before they delete them. Mail builds up in a small portion of those mailboxes. In some cases, the same message can be fetched several times from the server.
A lightweight IMAP user base represents users that enable premium broadband Internet services, including most of the advanced features of their messaging systems like message searching and client filters. This user base is similar to heavyweight POP with regard to message sizes, number of recipients, and number of messages sent and received by each concurrent connection. Lightweight IMAP users typically log in for hours at a time and delete most or all mail before log out. Consequently, mail stacks up in a mailbox during a login session, but user generally do not store more than 20 to 30 messages in their mailboxes. Most inboxes contain less than 10 messages.
A mediumweight IMAP user base represents sophisticated enterprise users with login sessions lasting most of an eight hour business day. These users send, receive, and keep a large amount of mail. Furthermore, these users have unlimited or very large message quotas. Their inboxes contain a large amount of mail that grows during the day, and is fully or partially purged in large spurts. They regularly file messages into folders and search for messages multiple times per hour. Each concurrent client connection sends approximately eight messages per hour. These users send messages with an average of four recipients and have the same message size mix as the Heavyweight POP and Lightweight IMAP user bases.
A mediumweight Messenger Express/Communications Express user base is similar to Mediumweight IMAP. This user base has the same message size mix as Mediumweight IMAP, Lightweight IMAP, and Heavyweight POP. And, the message delivery rates are the same as Mediumweight IMAP users.
It is likely that you will have more than one type of user base in your organization, particularly if you offer more than one client access option. Once you identify your user bases from these categories, you will test them with your usage profile and with a load simulator, described in Using a Messaging Server Load Simulator.