For example, if a LAN is linked to a campus mainframe, and another, incompatible LAN is also connected to the same mainframe, then individuals on both LANs can communicate through the mainframe even though they cannot talk directly to each other. And if that mainframe computer is also connected to Internet, then users on both LANs can also communicate worldwide. And in a multiple LAN environment without mainframe access, a way around the communications roadblock is to make sure that one of the LANs also has a link to Internet, again allowing Internet to act as the hub for e-mail. Most e-mail systems are not hard to use, but lack of connectivity that prevents you from communicating with colleagues is a severe limitation, and will eventually render the system unusable. Further, some people begin with one e-mail system, but soon find that they want to communicate with people using other systems.
Different systems utilize different commands and require additional training.
Sometimes people need to use three or four different e-mail systems. Not only does it require time to learn the various commands and facilities of each mail system, one must also check each system frequently to determine if new mail has arrived. A more sensible approach is to attempt to use only one e-mail system, with one mailbox. Functions may include appointment calendars, to-do lists, meeting and facilities scheduling, and project management tools. However, such tools are available separately, and their inclusion in a given e-mail package should not sidetrack the decision to give connectivity high priority.