Email blacklist monitoring is offered in three forms. Each of them has a separate audience and purpose. Any of them will help you ensure that critical email is delivered.
The two types of blacklists monitored are realtime blacklist dns(rbldns) and right hand side domain(rhsbl) blacklists. While there are hundreds of blacklists available, many are obscure or limited to special purposes. The core blacklists that affect email delivery have been selected for monitoring.
Several studies of ad campaigns suggest that appearing in one of the core blacklists can cut email deliverability from approximately seventy percent to around thirty five percent. As email ads are already suffer from lower delivery rates, you can imagine the impact that a blacklist can have on the deliverability of business email.
Mail server blacklist monitoring checks whether the ip address assigned to your outbound smtp server appears on any of the blacklists. The check starts by resolving the dns A record assigned to your email server host name. The corresponding ip address is then used as the input for the blacklist scan. If the address appears in any blacklist an alert is sent. The details are available in the user control panel. This type of blacklist scan is scheduled six times a day.
Domain blacklist monitoring detects whether your domain name appears in any right hand side blacklists. The input for the blacklist scan is your domain name and not the email server name. If the domain name appears in any blacklist an alert is sent. The details are available in the user control panel. Righthand side blacklist scans are scheduled every 4 hours.
Bulk ip address blacklist monitoring is similar to the mail server blacklist monitoring service. The difference is that the ip addresses specified as a /24 cidr net block are used directly as the input to the blacklist scanning process. This type of monitoring is suitable for network operators and hosting companies who cannot afford to permit the blacklisting of one address to affect the deliverability of surrounding addresses. If any address is blacklisted an alert is sent. The details and a address map are available in the user control panel. A sample can be found here. Bulk ip address blacklist scans are scheduled every 24 hours.