Email Blacklist Intermediate

Email blacklists-check and delist your IP or domain

If your email is bouncing or going to spam, your server IP or domain may be on an email blacklist. How to check, what causes listing,

UnderHost NOC Network Operations

6 min read Updated June 2026

On this page

What is a blacklist?
Check if you are blacklisted
Common causes
How to request delisting
Preventing future listings

Email blacklists (also called RBLs-Real-time Blackhole Lists) are databases of IP addresses and domains known to send spam. When mail servers receive your email, they check these databases. If your IP or domain is listed, mail may be rejected outright or sent to spam.

What is an email blacklist?

Major blacklists used by mail servers worldwide include Spamhaus (SBL, XBL, PBL), Barracuda BRBL, SORBS, SpamCop, and SURBL. Being listed on any major blacklist can significantly impact your email delivery.

Check if you are blacklisted

Find your server IP in CustomerPanel → Services → your service → service details
Use MXToolbox Blacklist Check or similar tools to check your IP against major blacklists
Or use MXToolbox Blacklist Check
If listed, note which blacklist(s) and the reason given

Common causes of blacklisting

Malware or hacked account-a compromised website or email account sending spam without your knowledge is the most common cause
Sending too much email too fast-bulk sends that look like spam patterns
Missing or incorrect SPF/DKIM records-unauthenticated email is treated with more suspicion
Missing PTR (reverse DNS) record-many mail servers require a valid PTR record; see rDNS/PTR setup guide
Spam trap hits-sending to addresses that are honeypots set up to catch spammers
User complaints-recipients marked your mail as spam

How to request delisting

Each blacklist has its own delisting process. General steps:

Fix the root cause first-if you're listed because of spam, stop the spam before requesting removal. Requesting delisting without fixing the cause will result in re-listing.
Visit the blacklist provider's website and look for a "removal request" or "self-service delisting" form
Enter your IP address and follow their instructions
Most major blacklists (Spamhaus, Barracuda) delist automatically after a period if spam stops

Blacklist	Delist process
Spamhaus SBL	Submit removal request at spamhaus.org-explain what spam was sent and what fix was applied
Spamhaus PBL	PBL lists residential/dynamic IPs by default. Request removal if you're a legitimate server.
Barracuda BRBL	Self-service removal at barracudacentral.org/rbl/removal-request
SORBS	sorbs.net has a delisting form-requires providing email and explanation
SpamCop	Listings expire automatically after 24 hours if spam stops

If delisting is complex or you can't determine the cause, open a support ticket-include your server IP and which blacklist you're listed on. UnderHost can investigate whether the issue is from another account on the shared server.