InboxGrade

Listed on Mailspike reputation list

The sending IP appears on one of Mailspike's reputation zones (bl.mailspike.net or z.mailspike.net), indicating observed behavior that scores poorly against its traffic model.

Impact — Medium impact

Mailspike feeds into SpamAssassin via the RCVD_IN_MSPIKE_* rules and into several commercial filters, so a listing typically adds 1-3 points to inbound spam scores at receivers that query it. Unlike binary blocklists, Mailspike grades IPs on a reputation scale from L5 (worst) to H5 (best), so delisting requires actually changing sending behavior rather than filing a one-time removal request. Expect degraded inbox placement at mid-sized ISPs and corporate filters, not hard rejections.

What causes it

  1. Sudden volume spikes from a previously quiet IP, which Mailspike's traffic model flags as snowshoe or compromised-account behavior
  2. High complaint rates or spamtrap hits accumulated over the trailing 7-30 day window Mailspike scores against
  3. Sending to large volumes of invalid addresses, producing bounce patterns consistent with list scraping or dictionary attacks
  4. Shared IP pool contamination where other tenants on the same /24 have poor reputation that drags the whole range down
  5. Recently warmed or rotated IPs with insufficient sending history to establish a positive reputation baseline

How to fix it

Confirm the listing and current reputation grade

Query both Mailspike zones directly to see which list the IP hit and what grade it carries. The reputation zone (rep.mailspike.net) returns a return code from 127.0.0.10 (L5, worst) through 127.0.0.20 (H5, best).

dig +short 4.3.2.1.bl.mailspike.net
dig +short 4.3.2.1.z.mailspike.net
dig +short 4.3.2.1.rep.mailspike.net

Stop sending from the listed IP and identify the trigger

Pause outbound mail from the affected IP and pull the last 7 days of logs. Look for bounce rate above 5%, FBL complaints above 0.1%, or unusual volume ramps. Mailspike will not delist an IP that is still exhibiting the behavior that got it listed, so fixing the source matters more than filing paperwork.

Request delisting through Mailspike's form

Once the root cause is fixed, submit the IP at the Mailspike delist page. Removal is manual and reviewed — reputation history is not wiped, so the IP must demonstrate clean traffic for several days before the grade recovers to H-tier.

https://www.mailspike.net/usc/lookup.html

Move transactional traffic to a reputation-managed IP

If the listed IP is yours alone, suspend sending and warm back up slowly (double daily volume per day, starting at ~50/day). If it is shared and you do not control pool hygiene, migrate transactional and critical mail to a provider that actively monitors Mailspike feedback and rotates poisoned IPs out of rotation.

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