Electronic Messaging Systems

A computer system for facilitating communications between users is configured for: (A) receiving, from a first user, one or more user watch area attributes; (B) using the one or more user watch area attributes to define a watch area; (C) receiving, from a second user, a message associated with a geographical location; (D) determining whether the geographical location is located within the user watch area; (E) at least partially in response to determining that the geographical location is located within the user watch area, subscribing the first user to a thread of messages that includes the message; and (F) dynamically adjusting a shape of the user watch area based, at least in part, on a factor selected from a group consisting of: (1) a number of message postings within the user watch area; and (2) a population density of an area that is within the user watch area.