Cisco Email Security Appliance

Email Security Appliance (ESA) provides comprehensive, simple, and fast-deploying security services for attacks initiated through email. Nowadays, spam and malware increase security complexity. ESA helps organizations to secure their email networks with low operating costs. ESA provides automated security policy settings, where the threat data is refreshed automatically every three to five minutes. It has a very flexible deployment choice and it also integrates with your organization's existing infrastructure. 

Cisco ESA is a virtual appliance that allows network administrators to create multiple instances wherever required in the existing network infrastructure. This virtual appliance runs on VMware ESXI hypervisor and Cisco Unified Computing System (UCS) servers.

Some of the main capabilities of ESA are:

• Threat intelligence: Provides fast, comprehensive protection of email. ESA has 100 TB of security databases updated daily, which cover approximately 150 million endpoints.
• Spam blocking: ESA's multi-layer defensive solution stops spam messages by filtering based on the reputation of the sender and deep analysis of the message. More than 80% of spam messages are blocked even before hitting the network.
• Graymail detection: Graymail is mail from marketing websites, social networking sites, and so on. ESA monitors Graymail senders and allows the administrator to take appropriate action to unsubscribe links.

The following is a list of Email Security Appliances (ESAs) and their capacity respectively: