Saving an equation-based replacement set of message recipients for future use

A set of recipients of an electronic message are identified. The recipients may be part of a first list. Each recipient of the first list may have had their name or other identifier (e.g., email address) entered by a user into one of various designation sections of a messaging interface. A second list is also entered into one of the various designation sections of the messaging interface. The first and second lists may be mathematically evaluated using a set operator to generate a third list. The third list may be referred to as a replacement set of recipients. Saving this third set as a new list may occur by saving an expression of a name/identifier of the first list, name/identifier of the second list, and the set operator. The saved third set may be selected for future message conveyances.