Real-Time Blacklists Remove 67% of Spam

A prospective ISP customer asked us today about the effectiveness of Mailspect Defense at the pre-span, scan and post-scan layers.  They asked what proportion of the email stream is ‘real or white emails’ versus ‘spam or black emails’ versus ‘gray or quarantine emails’.  We were surprised that the ISP didn’t know this data because Mailspect comes with a built-in reporting tool that tracks the number and composition of the email stream by hour and shows it to the system admin in a nice clean graphic.

Email Stream By Hour and Composition

These are data from the Mailspect internal email server that we shared with the ISP.  Looking at the pie chart, we pointed out that the key to antispam and antivirus efficiency is to remove as much spam in the pre-scan layer as possible.  The blue section labeled RBL [real-time black lists] shows that Mailspect Defense removed 67% of the email stream as spam in the pre-scan (or pre-queue for the technically precise) layer.  If you want to know which real-time blacklists we used to achieve such a high score, please contact

We did this analysis to help the ISP estimate the number of emails that would end up in quarantine (gray emails) so they could size the servers and storage needed for their implementation.  We estimated that 8% of the email stream will end up as gray email in the quarantine after being scanned by Cloudmark or Mailshell.  We provided them with a Quarantine Sizing Calculator to help them estimate the size of the quarantine digest store based on the number of emails per user per day, black and white email detection levels, and the number of days of quarantine retention.

We also demonstrated how to email the quarantine digest to each user everyday or use an RSS feed for the tech savy.

Mailspect Defense is an amazing product as proved by our near 100% renewal rate.

Recently Asked Question:  How much spam gets removed at the pre-scan or SMTP gateway layer using Real-Time Black Lists or RBL, also know as Blackholes ?

Subsequently, the ISP looked into its data and determined that it could remove 87% of spam at the pre-scan / pre-queue  /  at the SMTP gateway layer using well-configured real-time black lists or RBL.    It shows that ‘consumer’ email streams are dirtier than buisness email streams like Mailspect’s.


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