UCEPROTECT Blocklistings

This article explains UCEPROTECT Blocklists, why they are not a reputable Blocklist provider, and why being listed by UCEPROTECT does not affect the deliverability of emails sent through the Twilio SendGrid platform.



UCEPROTECT is a Blocklist that lists all of the IP addresses of any reputable email service provider including the entire Twilio SendGrid IP space.

UCEPROTECT ignores the RFC's stated principle of transparency, vaguely describing their listing criteria in such a way that no audit trail is possible, their sources and operating methodologies are not identified, and no mechanism exists to request information on why an IP address was placed on their Blocklist.



RFC6471 is an overview of the operational best practices for running a Blocklist. Among many reasons listed in this RFC, UCEPROTECT operates outside of the boundaries of a legitimate negative-connotation DNSBL due to offering "Express Delisting."

Per section 2.2.5 of the RFC, "Conflict of Interest":

It is generally considered entirely appropriate for a DNSBL to charge for access to it by its users -- the definition of a commercial DNSBL. However, the practice of requiring a listee to pay for delisting from a negative-connotation DNSBL steers perilously close to notions of extortion, blackmail, or a "protection racket". Even when such accusations are entirely unjustified, the practice causes uproar and damage to the DNSBL's reputation, if not the DNSBL mechanism as a whole.


UCEPROTECT and its effect on deliverability 

Our deliverability experts believe, and our research has confirmed, that being listed by UCEPROTECT causes little to no impact on deliverability. None of the major mailbox providers reference UCEPROTECT to decide inbox placement or blocking decisions. Less than 0.001% (one thousandth of one percent) of SendGrid email is sent to domains that use UCEPROTECT as a part of their anti-spam protocols.


Twilio SendGrid and UCEPROTECT

The UCEPROTECT site disclaimer is explicit that "The author reserves the right not to be responsible for the topicality, correctness, completeness or quality of the information provided," calling into question how any of the data from UCEPROTECT can be trusted.

With these facts in mind, Twilio SendGrid has taken a position that UCEPROTECT is not a legitimate Blocklist and as a result, these listings will not be actioned.

In the event of any changes or modifications to UCEPROTECT's listing criteria, or if our customers are adversely affected by their Blocklist, we will adapt this policy accordingly.


When to open a Support Ticket regarding UCEPROTECT

We are aware of these listings and are extremely confident that they will cause no impact for the vast majority of our users. If you have confirmation that an email delivery failed due to a UCEPROTECT Blocklisting, please open a Support Ticket so we can review your account.


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