Several people handling one address, such as support@ or sales@.
THE SIMPLE APPROACH
Create one mailbox and set it up on each person's computer using IMAP. Everyone sees the same inbox, the same folders and the same read and unread status.
Agree a convention: move handled messages to a Done folder, or flag them. Without one, two people reply to the same customer or nobody does.
THE FORWARDER APPROACH
Create a forwarder to several individual mailboxes. Everyone receives a copy in their own inbox.
Simpler to set up, but there is no shared state. Everyone sees every message as unread, and replies come from personal addresses rather than the shared one.
WHICH TO CHOOSE
IMAP shared mailbox for anything where tracking matters, particularly support and sales. Forwarders where the volume is low and it is obvious who deals with what.
REPLYING FROM THE SHARED ADDRESS
Add the shared address as an additional identity in each person's mail client, so replies go out as support@ rather than a personal address.
WHEN TO OUTGROW THIS
At real volume, a helpdesk system is the right tool. Shared mailboxes stop working when several people are busy at once.