Overview
Some email recipients or monitoring tools may report that IP addresses associated with Opensense are listed on the UCEPROTECT blocklist. This article clarifies what UCEPROTECT is, its relevance to email deliverability, and how Opensense addresses such listings.
What is UCEPROTECT?
UCEPROTECT is an independent blocklist that aggregates IP addresses based on its own unpublished criteria. It often lists broad IP ranges, including those used by major cloud providers and reputable email service platforms.
Key characteristics:
UCEPROTECT does not offer transparent or auditable listing criteria.
Its blocklist includes entire network ranges, which may include legitimate and high-volume email senders.
Delisting is only available through a paid “express” service, which is not consistent with industry standards for responsible blocklist operation.
Industry Best Practices
According to industry-recognized guidelines outlined in [RFC6471], blocklists that charge for delisting or lack transparency are not considered reliable indicators of email reputation. Specifically, the standard states:
“The practice of requiring a listee to pay for delisting from a negative-connotation DNSBL steers perilously close to notions of extortion... Even when such accusations are entirely unjustified, the practice causes uproar and damage to the DNSBL's reputation.”
Based on this and similar evaluations by deliverability professionals across the email industry, UCEPROTECT is not widely trusted or used by leading mailbox providers.
Impact on Deliverability
Opensense has conducted extensive monitoring and analysis regarding the deliverability impact of UCEPROTECT listings. Key findings include:
Major inbox providers such as Gmail, Outlook, and Yahoo do not reference UCEPROTECT in their spam filtering systems.
Less than 0.001% of Opensense email volume is routed to recipients that rely on UCEPROTECT as part of their filtering stack.
No measurable or legitimate deliverability failures have been linked to UCEPROTECT listings.
Opensense Policy
Opensense continuously monitors deliverability performance across our network. Based on all available data:
We do not escalate or intervene in UCEPROTECT listings, as they do not reflect actual risk or impact.
Listings of this nature are expected and commonly affect email platforms that send on behalf of many customers.
Our team prioritizes deliverability signals that are credible, traceable, and aligned with real-world delivery behavior.
When to Contact Support
If you believe a specific email message failed to deliver due to a UCEPROTECT listing, please reach out to our support team help@opensense.com and provide the following:
The full message headers and delivery logs
Any bounce or rejection notices received
The recipient domain where the issue occurred
Our team will investigate the issue in detail and provide guidance based on verified deliverability data.
Summary
UCEPROTECT is not a widely respected or impactful blocklist, and its listings are not indicative of any deliverability threat. Opensense does not consider UCEPROTECT listings actionable, as they do not reflect the quality, reputation, or delivery performance of our platform.
We remain committed to maintaining excellent deliverability and transparency for all of our customers.