Computer-executable methods and programs for formulating a planning recommendation for a messaging platform. Mailbox data is received specifying a projected maximum number of mailboxes. Growth assumption data is received that specifies a change in average message size of messages. Traffic assumption data is received that identifies a portion of message traffic projected to occur during any recurring time interval for which message traffic has previously exceeded a threshold. Baseline data is received specifying maximum performance capabilities of the messaging platform. Messaging platform data is received specifying a quantity of messages accepted, stored, deleted, and/or retrieved. A planning recommendation is generated by applying an algorithm to the mailbox data, traffic and growth assumption data, baseline data, and messaging platform data. The planning recommendation is placed into a physically tangible, humanly discernible form by printing the recommendation, displaying the recommendation, or outputting the recommendation in audible form.