The Mailspike Z - Zero-Hour Data Blacklist (ZBL) is a real-time IP-based blacklist that identifies addresses participating in distributed spam waves based on immediate viral behavior rather than historical reputation.
The Mailspike Z - Zero-Hour Data Blacklist (ZBL), also known as ZBI, is a real-time blocklist that identifies IP addresses participating in distributed spam attacks. Unlike other blacklists that rely on historical reputation, the ZBL focuses on detecting immediate, viral spamming behavior shared across multiple IP addresses. Its goal is to stop new and emerging spam waves as they happen.
Technically, when an IP address is on this blacklist, a DNS query for its A record to z.mailspike.net will return 127.0.0.2. Mailspike recommends that mail server administrators who use this blocklist should reject emails from listed IPs at the MTA (Mail Transfer Agent) level, effectively blocking them before they reach inboxes.
Typical reasons for an IP address to be listed on this blacklist include:
The ZBL blocklist is operated by Mailspike Technologies, Lda. The company has a significant history in the email cybersecurity field. It originated as Anubisnetworks in Portugal in 2006, developing a cloud-based email security gateway for telecommunication companies. After being acquired by Bitsight Technologies in 2014, the email security division was spun off in 2019 to form Mailspike Technologies. Today, the company continues to focus on providing innovative email security solutions and managing reputation blocklists like the ZBL.
Mailspike provides a straightforward delisting process. Before you request removal, it is critical to identify and fix the root cause of the listing. If the problematic activity persists, your IP address will likely be listed again. For example, if your server was compromised, ensure it is secure before proceeding.
Once the underlying issue is resolved, you can request removal using their IP reputation and delisting form. Delisting is typically processed automatically within 6 to 36 hours. However, if the listing is due to involvement in a known spam botnet, delisting will only occur after Mailspike's systems verify that the malware threat has been mitigated.
The impact of being listed on the Mailspike ZBL is considered medium. Since Mailspike recommends that its users block email at the connection level (MTA), a listing can cause significant email delivery failures. Any mail server or receiving system that uses this particular blacklist (or blocklist) will reject your emails outright. Given Mailspike's history and user base, which includes telecommunication companies and other businesses, this blacklist can affect your ability to reach a wide range of recipients.
Organization
Zone
Type
Impact
Delisting
Organization
Zone
Type
Impact
Delisting
19 resources
Besides Spamhaus, what blocklists are important for email marketers to monitor?
What are examples of insignificant or ineffective email blocklists?
What is the Spamhaus content hash blocklist and how does it compare to DCC, Vipul's Razor, and Cloudmark?
What does a UCEPROTECTL3 blocklist mean for email deliverability and pristine spam traps?
What is the PSBL (Passive Spam Block List) and how does it work?
What is the current status and relevance of the NJABL email blacklist?