Blocklist
MetaDefender Cloud Email Security supports a global IP address & sender email blocklist. This list can be used to prevent specific IP addresses/ranges and/or senders to submit emails for processing.
Overview
The Blocklist is available by navigating to Settings > Blocklist.
Emails rejected by the Blocklist can be found among the refused emails in Audit > Refused Emails.
Adding blocklist entries
Block IP address
To block a specific IP address, click on the Add sender IP address to filter option and specify the IP (v4 or v6) address and click Save to store the changes. Any attempt to send emails from that specific address will be rejected by MetaDefender Cloud Email Security.
Block IP range
To block CIDR IP address range, click on the Add sender IP address to filter option and specify the range, for example: 192.168.129.23/17 and click Save to store the changes.
Block sender email address
Blocking a specific sender is done by clicking on Add sender domain or address filter and specifying the address to be blocked. Please note that a Regular Expression can also be used to block multiple addresses with a single filter entry. If a regular expression is used as value, make sure to change the drop-down value to Regex.
Block sender email domain
To block a specific sender domain, simply specify the email domain to be blocked. If using a Regular Expression to define a domain filter, make sure to select Regex in the drop-down to the right of the value entered.
Blocklist responses
Any blocklisted clients attempting to send emails to MetaDefender Cloud Email Security will receive the following SMTP responses:
IP addresses/ranges
550 IP address '1.2.3.4', is blocklisted, rejecting
Email addresses/domain
550 Email address 'spammer@organization.com', is blocklisted, rejecting