Duplicates & Suppression - FAQs
What is Duplicate Prevention?
Duplicate Prevention prevents the same recipient from receiving more than one piece of mail from your account within a 36-hour window, account-wide across all lists and campaign types.
How does the 36-hour window work?
When mail is sent to a recipient, thanks.io records the send timestamp. If another send is attempted for the same recipient within 36 hours, it is blocked and marked "Duplicate Prevented." The window resets after 36 hours.
Can I disable Duplicate Prevention?
Yes. Go to Account Settings → Mail Preferences and toggle off Enable Dedupe Failsafe under the Duplicate Prevention section. When off, duplicate checks are disabled account-wide. Gift cards are unaffected either way.
What is a Suppression List?
A Suppression List contains recipients who should never receive mail from your account. They are permanently skipped on all future sends, regardless of which list or campaign triggers the send.
How is a Suppression List different from Duplicate Prevention?
Duplicate Prevention is a temporary, time-based block (expires after 36 hours). A Suppression List is a permanent exclusion. Use Suppression Lists for opt-outs; Duplicate Prevention handles accidental double-sends.