Some now, some later? Selecting a 'lot size' of e-mails to process at one time

Efficient allocation of e-mail processing time will have a major impact on an organisation's productivity. When a Knowledge Worker (KW) is processing an e-mail, should she process all the e-mail in her inbox, or allocate time for e-mail and other activities? The KW's time may have varying values in different periods depending on other activities required of her in each period. Not answering e-mails quickly or rescheduling daily tasks to answer e-mails may incur a cost. On the other hand, valuable time spent on e-mail also results in a cost. These two types of costs are analogous to backorder/holding and production costs in inventory models. The objective is to find an optimal e-mail time allocation policy that minimises the total cost of processing all e-mails in a timely manner. This study, by adapting a capacitated lot sizing approach, demonstrates an interesting application of inventory models in a service area where time is the commodity being managed.