Skip to content
Go to dashboard

6.3Blocklist checks

A blocklist (also called a blacklist) is a public list of IP addresses known to send spam. Mail from a listed address is often rejected. In the record type list, this check is called BLACKLIST.

Set it up#

  1. Follow the steps in "Create a DNS monitor" above. Choose the record type BLACKLIST.
  2. In domain or IPv4 address, enter your domain, such as acme.io, or one IPv4 address, such as 203.0.113.7.
  3. Select create monitor →.

The form hint says: "Checks the domain's addresses and its mail servers' against 5 spam blacklists. Down if any lists one."

A blocklist check takes no expected values. Choosing BLACKLIST clears any you typed. Through the API, leave out expectedValues. If you send them, the API returns a BLACKLIST monitor takes no expected values.

What obsrvly checks#

  • For an IPv4 address: that address.
  • For a domain: the domain's own IPv4 addresses and the IPv4 addresses of its mail servers (MX records).
  • At most 8 addresses are checked in each run. If your domain has more, only 8 are checked. To cover the rest, add a monitor for each extra IPv4 address.
  • Private addresses are skipped.
  • IPv6 addresses cannot be checked, in the dashboard or the API.
  • Each address is checked against 5 blocklists: bl.spamcop.net, psbl.surriel.com, b.barracudacentral.org, dnsbl-1.uceprotect.net and all.s5h.net. Spamhaus is not one of the lists.
  • Only IP addresses are checked. The domain name itself is not checked against domain blocklists.

Results#

ResultMessageWhat to do
Up—None of the lists includes your addresses.
Downlisted on bl.spamcop.net (203.0.113.7)Fix the cause of the spam. Then contact the list named in the message.
Downblacklists: acme.io has no public IPv4 address to checkCheck that the domain points to a public IPv4 address, or enter the address itself.
Downblacklists: only IPv4 addresses can be checkedEnter an IPv4 address or a domain.

If an address is on any list, the check is down, even if other lists did not answer. If several are listed, the message names each one, such as listed on <list> (<ip>), <list> (<ip>).

If most lists do not answer, the result is Could not run with this message: "The blacklist check could not be run: too few of the blacklists answered our queries. This says nothing about your mail servers." You do not need to do anything. It does not count toward uptime or alerts.

Through the API, each result's metadataJson shows how many lists answered. The dashboard does not show this.

metadataJson of a blocklist result
json
{"blacklist": {"lists": 5, "answered": 4,
               "unanswered": ["…"]}}

Last updated