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An important concept about the email server configuration is open relay. A server that works in open relay processes messages between senders and recipients out of the server's domain, that actually can even be non-existent. Obviously, IPBrick doesn't work as an open relay, it only forwards Internet emails to domains that are explicitly indicated.
It is important to mention four very simple and decisive concepts in E-mail configuration:
Locally delivered domains: E-mail addresses with destination to the IPBrick server itself, that is, the associated e-mail accounts are in the local network. E-mails that are in the queue and whose recipient is one of these domains are not sent to another server in order to be delivered. The domains served by the machine have to be correctly configured in each DNS domain server. That is, the "E-mail servers" of these domains have to be configured to this machine.
Authorized relay domains: IPBrick forwards all the messages that have their domains in this list and will be accepted by the server to a queue list. Messages to other recipients that don't belong to this domains won't be accepted by the server (please see 3.3).
Relay networks definitions: IPBrick relays to any domain as long as the e-mail is sent from his corresponding internal network. If there are different internal IP networks it is necessary to add these networks to the list. This way all machines in the networks are able to send e-mails to other domains using IPBrick as a relay server. The Other networks (Internet IP's) could use this SMTP server but only with TLS authentication. So someone in Internet that want to use the IPBrick's SMTP to send email is forced to authenticate with his LDAP username/password;
SMTP Routes: SMTP routes are configured when you want e-mails to follow a certain way (server) in order to find their recipient. Normally, a SMTP route is defined by default (showing the SMTP route and leaving the Domain empty).When the server is not correctly registered with the IP name in the Internet DNS, you have to define a SMTP route. In this route it should be either the server responsible for the forward of company e-mails or the SMTP server of the ISP used by firms to access the Internet. This configuration is necessary because certain e-mail servers make additional verifications of the sending server authenticity. If they can't resolve the server name into the corresponding IP address (reverse DNS check), the mail may be deleted or sent back as SPAM. In case no SMTP route is used the server tries to send the mails in the queue by his own. With the help of the DNS registrations he tries to find the recipients directly in the Internet.
Each e-mail configuration option has a link to Insert new entries (Figure 3.32).
The domains for local delivery (domains with IPBrick serves) and relay (domains which IPBrick forwards) can be edited and/or deleted. The exception is the domain whose name is the same as that of the machine in the local networks or that of the local domain in the relay.
Note: To make IPBrick relay e-mails to another server holding the accounts, the firm base domain has to be retreated from the domains served by IPBrick, since it is a domain served by IPBrick by default.
By default IPBrick only forwards email messages that come from its private network. If there are different internal IP networks, they should be added to allow them to send messages.
There are two different types of SMTP routes:
smtp.exchange.telepac.pt.
195.22.133.45.
In the following you are given two examples of configurations, one with an IP for a specific domain and another configuration for the same domain with the FQDN:
First Example: Domain : abzas.miz SMTP route : 195.22.133.45 Second Example: Domain : abzas.miz SMTP route : smtp.exchange.telepac.pt
An important configuration is that of a machine relaying e-mails. Whenever you add in this situation a SMTP route by default (without indicating the domain) you have to add another SMTP route to forward e-mails do the internal e-mail server. In the following you can see an example of such a configuration.
In this configuration IPBrick is relaying all the e-mails comming to an internal e-mail server called accounts. IPBrick have a second route to deliver all the mail to the Internet by the smarthost smtp.isp.pt:
Domain: domain.com SMTP route: accounts.domain.com Domain: SMTP route: smtp.isp.pt