We’re always happy to investigate new blacklists to see how they work for our customers and how they provide additional information on our customers’ email deliverability.  If anyone ever has a blacklist that they suggest we add, please email us.

Over the last few weeks, we’ve given SPFBL, a Brazilian-based DNS Blacklist, a trial here at MxToolbox.  Like all new Blacklists, our trip included display of results with low severity.  However, during the trial we noted that the majority of customers reporting issues with this blacklist were due to simple, and routine reverse DNS issues.  For example, reverse DNS might point to a 3rd party load balancer application, which in no way should break email delivery.

Since this is the case, we’ve decided to suspend use of SPFBL until utility of the list changes.

Recently, we’ve received a number of enquiries about delisting with Protected Sky.  For the last week or so, Protected Sky has had a maintenance notice reminding users that delisting is not available.  Over the weekend, they added another announcement:

Automatic removal will occur for IPs that are seen to be clean

MxToolbox Support is currently trying to contact Protected Sky for clarification, but we have an operating theory.  Currently, we believe this to mean that they have a system in place to automatically delist an IP address if it is not captured in one of their spam traps or reported by one of their customers as spam.

Once we have confirmation or update from Protected Sky, we will update this post with more information.