Update source is a resource containing updates for Kaspersky Secure Mail Gateway databases.
The main update source is Kaspersky Lab's update servers. These are special Internet sites which contain updates for databases and application modules for all Kaspersky Lab products. If you connect to the Internet via a proxy server, you have to configure the proxy server connection settings.
To reduce the amount of Internet traffic, you can configure Kaspersky Secure Mail Gateway to update databases from a custom update source. HTTP or FTP servers or local folders on your computer can serve as custom updates sources.
If Kaspersky Secure Mail Gateway is managed using Kaspersky Security Center, you can select Kaspersky Security Center as the update source.