What is a blocklist (RBL/DNSBL)? A Plain-English Guide
A blocklist (RBL or DNSBL) is a published list of IPs or domains believed to send spam. Being listed on Spamhaus, Barracuda or SORBS can block your mail at many receivers.
Why it matters for deliverability
Understanding a blocklist (RBL/DNSBL) is part of why and how to get delisted. Get it right and more of your mail reaches the inbox; get it wrong and even legitimate mail can be filtered.
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How Rainmail helps
Rainmail sends from your own domain on a dedicated, isolated IP with SPF, DKIM, DMARC, reverse-DNS and managed warm-up handled for you, plus an AI that watches your list health and deliverability — and it welcomes the senders Amazon SES, SendGrid and Mailchimp reject, from $8. Run the free 10-second checker or see plans.