Definitions

There is a link called Definitions (see Figure 3.32 and Figure 3.33) to define characteristics of the e-mail server:

• Message maximum size: It's the global message maximum size of a sending message
  Value by default: unlimited.
• Maximum time to hold the message in the server: Maximum time the message will be in mail queue
  Value by default: 604800 seconds (7 days)
• Maximum number for simultaneous SMTP connections: Number of connections that the server can support
  Value by default: 20
• Incoming message timeout: Maximum time to receive a single message in server. If reached it will timeout
  Value by default: 1200 seconds
• Outgoing message timeout: Maximum time to send a single message. If reached it will timeout
  Value by default: 1200 seconds
• Reject emails from invalid domains: The server will reject incoming mail if the sender's domain MX record don't exist, so it will be invalid.
  Default value: Yes
• Reject emails from invalid servers: The server will reject incoming mail if the sender's FQDN don't have a reverse DNS record.
  Default value: No

Figure 3.32: E-Mail - Definitions 1/2

Figure 3.33: E-Mail - Definitions 2/2

In this interface it is even possible to define permissions of sending and receiving e-mails:

• Valid internal recipients: This list is important to fill in order to protect the server from a mailbomb attack. Here should be listed all the internal valid email addresses. If the list is empty all the internal recipients will be accepted (Figure 3.34);
• Invalid senders: A list with e-mail addresses that are not allowed to send email ((Figure 3.35).

Figure 3.34: E-Mail - Definitions - Valid internal recipients

Figure 3.35: E-Mail - Definitions - Invalid senders