Email Blacklist Check: Is Your IP or Domain Listed?
One blocklist entry can tank your deliverability overnight. Here is how to check, why it happens, and how to get off.
What email blocklists are
Blocklists (also called blacklists) are real-time databases of IPs and domains known to send spam. Mailbox providers check these lists when deciding whether to accept or filter your email. If you are on a major list (Spamhaus, Barracuda, Spamcop), your inbox placement drops immediately.
How to check your status
GlockApps — checks your sending IP against 50+ blocklists as part of every spam test, with ongoing monitoring on paid plans
MXToolbox — free single-IP lookup against major lists
MultiRBL — free multi-list checker
Check your IP against 50+ blocklists with a free GlockApps test.
Sending to spam traps (old addresses reactivated as traps)
Suddenly spiking send volume without warmup
Compromised sending infrastructure
Shared IP with another bad sender
How to get delisted
Identify which list you are on (GlockApps or MXToolbox will tell you)
Fix the root cause (list hygiene, reduce complaints, secure infrastructure)
Submit a removal request through the blocklist's website
Wait — most lists process requests within 24–72 hours
Monitor to ensure you do not get re-listed
Evidence & transparency. Checked against public data: blocklist operator documentation and delisting procedures. Not independently tested by us: delisting turnaround times. Reader should verify: specific blocklist policies at each operator's site. Last reviewed: June 2026.
Frequently asked questions
How often should I check blocklists?
At minimum before every major campaign. GlockApps paid plans include continuous monitoring with alerts.
Can I be on a blocklist without knowing?
Yes. That is why monitoring matters — you may not notice until open rates drop.