Email Filtering - Inbound and Outbound Filtering

Inbound and Outbound Filtering

Mail filters can operate on inbound and outbound email traffic. Inbound email filtering involves scanning messages from the Internet addressed to users protected by the filtering system or for lawful interception. Outbound email filtering involves the reverse - scanning email messages from local users before any potentially harmful messages can be delivered to others on the Internet. One method of outbound email filtering that is commonly used by Internet service providers is transparent SMTP proxying, in which email traffic is intercepted and filtered via a transparent proxy within the network. Outbound filtering can also take place in an email server. Many corporations employ data leak prevention technology in their outbound mail servers to prevent the leakage of sensitive information via email.