Before you create a user mailbox, you should create a mail domain. You can do it in the tab “Domains and mailboxes”, by pressing the button “Add” - “Mail domain”. If you want to exchange letters only within your local network, you can specify any domain name that you want, otherwise you can set up real mail domain that belongs to your organization. If you mark the “Create DKIM-signature” in settings, then it will be added automatically.
With double click on the account that has been already created, it would be open with pre-created DKIM-key, which you can copy if necessary.
Then, marking the chosen domain, you can add users mailboxes inside it. The server will ask you for a mailbox name, password and the user to which this mailbox will belong. You can add a quota if necessary – maximum amount of space on the ICS hard drive that this user’s letters can fill. After the quota is exceeded, user would not be able to receive letters anymore. By default quota is disabled.
You don’t need to create a mailbox for each mail name that you will need to use. You can also create a shortcut to this mailbox. Then, for example, all letters that are sent to the email@example.com mailbox, would be redirected to the real firstname.lastname@example.org mailbox.
Important: when creating mail domains and mailboxes the corresponding domains and account will appear in the “jabber-server” service. It works the other way around as well.
ICS mail server can act as a mail gateway (relay), which will resent through itself all messages, destined to some domains, to another (interior) mail server. Basically, it’s a mail server which connects two logically divided networks.
ICS mail gateway, when acting as a mail relay, also checks all messages that go through it, for spam and viruses.
If you want to add a domain, for which the final receiver will be another mail server, on ICS, you should add “Domain with redirection” in the “Domains and mailboxes” tab.
For example, if you need to redirect mail for email@example.com to the mail server 192.168.90.3, you need to set up domain with redirection like on the screenshot below:
Important: when receiving mail for a addressee that doesn’t exist in the internal mail server, the mail gateway will be responsible for notifying the sender when the letter can’t be delivered. So, the mail queue is flooded with messages when the addressee is unavailable. For mail domain to be available from the global network and could exchange messages with other servers in global network, you need to setup DNS-records.
After creating user mailboxes, users can connect to ICS mail server using mail clients (like Mozilla Thunderbird or Microsoft Outlook), or use mail web-interface.