Email Blacklist
An email blacklist (or blocklist) is a real-time database of IP addresses and domains identified as sources of spam.
What Is Email Blacklist?
Blacklists are maintained by organisations like Spamhaus, Barracuda, and SORBS. When your sending IP or domain appears on a blacklist, email servers that reference that list will reject or filter your emails. Getting blacklisted typically happens after sending to spam traps, receiving excessive spam complaints, or exhibiting spam-like sending patterns. There are dozens of blacklists, and some carry more weight than others — being on Spamhaus is far more damaging than being on a smaller, less-referenced list. Delisting requires identifying and fixing the root cause, then submitting a removal request.
Why It Matters for Newsletters
A single blacklisting can cause your emails to be rejected by major email providers worldwide. For newsletter creators, this means your entire subscriber base may stop receiving your content overnight. Blacklisting often happens without warning, and recovery can take days to weeks.
Best Practices
- Monitor your domain and IP against major blacklists regularly
- Investigate and fix the root cause before requesting delisting
- Keep spam complaint rates below 0.1%
- Never send to purchased or scraped email lists
- Set up alerts for deliverability metric changes that might indicate a listing
How Aldus Handles This
Aldus sends through Resend, which actively monitors and maintains the reputation of its infrastructure. If a blacklisting issue ever affects your domain, Aldus's deliverability monitoring will alert you and guide you through resolution.