Suppression List Matcher
Reviewed: 18 September 2026
A suppression list is the set of addresses you must not mail again — people who unsubscribed, hard bounced, complained, or whom you blocked yourself. Sending to a suppressed address hurts deliverability and can breach anti-spam rules. The ListGuard matcher removes every match from a list before you send.
How matching works
You upload two things: the list you want to send to, and the suppression list you want protected (an export from your email platform, or your own file).
Normalization runs first. Addresses are trimmed, lowercased and unwrapped, so Jane@Example.com and jane@example.com match as the same person. Matching happens on the normalized address, first occurrence semantics are deterministic, and the report shows exactly how many addresses were suppressed.
You download the clean list. Every suppressed address is out, with a report of what was removed and why.
The storage exception, in plain language
By default, ListGuard does not store the addresses you upload. Suppression lists are the documented exception: if you choose to save a suppression list, it is stored so future runs can keep protecting those addresses. You control what is saved, and the full data-handling description is on the security page and in the privacy policy.
What this is not
The matcher is not a persistent suppression-management platform: it does not collect unsubscribe events from campaigns, sync with your email provider in real time, or manage per-contact preferences. It protects the lists you run through it, using the suppression data you supply or choose to save. If you need campaign-level unsubscribe automation, that lives in your email platform.