An email server used by more than one company or sender. Shared servers are less expensive to use because the broadcast vendor can spread the cost over more users. However, senders sharing a server risk having emails blocked by major ISPs if one of the other users does something to get the server’s IP address blacklisted. See dedicated server.

The 3 Things To Avoid When Emailing Your List
When you decide to have an opt-in list, it is not just a matter of sending your subscribers your promotional newsletters or catalogs.