# Blocklist (blacklist): what it is and how it works
> A blocklist (blacklist) is a database of IPs, domains or senders regarded as spam sources, whose messages are blocked or filtered.
URL: https://www.zorraquino.com/en/dictionary/digital-marketing/blacklists.html

# Blocklist (blacklist)

A blocklist, traditionally called a blacklist, is a database of IP addresses, domains or senders regarded as sources of spam or abuse, whose messages are blocked or filtered

What it means, how it is used and where it comes up, with its related concepts.

[The whole glossary](https://www.zorraquino.com/en/dictionary)

## What it is and how it works

In email there are two levels. First, public DNS-based blocklists (DNSBLs) maintained by specialist organisations and checked by many mail servers to reject or flag messages. Second, each mailbox provider’s own filters, which take into account spam complaints, bounces, authentication and how users interact with messages.

A legitimate sender can end up on a blocklist by mailing purchased or outdated addresses, hitting spam traps or accumulating complaints. Getting removed usually requires fixing the cause and requesting delisting. In computing, “blocklist” is increasingly preferred to “blacklist”, and the opposite concept is the allowlist.

Also known as

Blacklist, DNSBL

Topics

[Marketing and sales](https://www.zorraquino.com/en/dictionary/category/marketing-y-ventas)

## Related concepts

- [Allowlist (whitelist)](https://www.zorraquino.com/en/dictionary/digital-marketing/whitelists.html)
- [Spam](https://www.zorraquino.com/en/dictionary/internet/spam.html)
- [Email deliverability](https://www.zorraquino.com/en/dictionary/digital-marketing/deliverability.html)