I've setup an email address for a new website and now I need it to be able to be accessed by multiple users who can setup the email account on their computer and read the Inbox. Some users use Mac some use Windows. Because there will be multiple users the likelihood is that emails might be deleted before other users have read those emails. Which type IMAP or POP do I setup the account in on the multiple users computers? Or is there a better way to ensure that all incoming and outgoing messages are held on the account for all users to read? Thanks in advance.
The only reliable way to ensure this is to create separate accounts, one for each user.
Most mail systems can be easily set up to "forward" or "alias" one recipient's mail to multiple mailboxes; often as simple as adding a
shared: usera userb userc
This way, all users will receive a fresh, marked as "unread", copy of the message, and deleting one will not affect others.
People do frequently take offense at being suggested better methods than the ones they think should work. So if you have to choose between IMAP and POP, you will need to choose POP – and if possible, configure the server to disallow message deletion, as some users may accidentally configure their mail clients to "fetch and delete" before other users get the messages.