Definition
An email suppression list and a blacklist are different control mechanisms. A suppression list is your internal list of addresses you must not email, such as unsubscribes, bounces and spam complainants, managed by you for compliance and hygiene.
A blacklist (or blocklist) is an external list maintained by monitoring services or mailbox providers that flags IP addresses or domains sending unwanted mail. Being listed typically causes delivery failures or delays.
They intersect: mismanaging your suppression list can lead to behavior (complaints, bounces, spam traps) that gets you blacklisted. Maintain your suppression list well to protect yourself from being placed on external blacklists.
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Related Glossary Terms
AI Content Detection
AI content detection refers to the growing ability of email clients, spam filters and consumers to identify machine-generated email copy. It matters for deliverability, trust and engagement in an era of mass-produced AI marketing email.
Batch Sending
Batch sending is the practice of delivering a single email campaign to a large list in groups or waves rather than all at once.
Bounce Classification
Bounce classification uses SMTP codes (550, 551, 552, 553, 554, 450, 451, 452) and enhanced status codes to categorise permanent and transient delivery failures.
Complaint Rate
Complaint rate is the percentage of delivered emails that recipients mark as spam, a key indicator of sender reputation and list quality.
DMARC Alignment
DMARC identifier alignment determines whether the domain in the From header matches the domains used in SPF and DKIM authentication. Strict or relaxed.
Acceptance Rate
Acceptance rate is the percentage of emails submitted for delivery that are accepted by the recipient's mail server, representing the first deliverability checkpoint before inbox placement is determined.
Frequently Asked Questions
It is your internal list of addresses you must not email, such as unsubscribes, bounces and complainants, kept for compliance and list hygiene.
A blacklist is an external list flagging IPs or domains that send unwanted mail, maintained by services or providers, causing delivery failures or delays when you are listed.
Neglecting your suppression list causes complaints, bounces and spam-trap hits that can get your sending IP or domain listed on external blacklists.