Act-On allows duplicate email addresses inside the same list, but duplicates are automatically suppressed at send time. Cleaning them up reduces the "not sent / suppressed" counts that show up in Sent Message Reports, and it improves the overall quality of your list. Use this tool when you need to tidy up a specific Marketing List or a list under Other Lists.
Who does this: Marketing ops maintaining list hygiene
Time needed: A few minutes per list, longer for heavily duplicated ones
Why this matters: Duplicates inflate your list counts, skew engagement rates, and produce confusing "suppressed" results in send reports. Cleaning them up gives you a list size you can actually trust and metrics that reflect real recipient behaviour.
In plain English: This tool looks inside one list, finds any email address that shows up more than once, and lets you pick which record to keep.
Quick Reference (Advanced Users) - Click to Expand
- Audience Center recommended: the All Contacts structure prevents most duplicates at the source.
- Marketing Lists: duplicate cleanup is done list by list.
- Delete Duplicates: shows every email address with more than one record and lets you keep or delete individual versions.
- Impact: cleaner lists, fewer suppressed sends, more trustworthy engagement metrics.
Try it like this: Open the list where your most recent send showed a spike in "suppressed - duplicate" results, run Delete Duplicates, and remove the extra records so future sends report cleaner numbers.
When should I delete duplicate records?
Most accounts cut their duplicate rate dramatically just by managing data from Audience Center > All Contacts. That said, Delete Duplicates is worth running when:
- A recent send shows an unusually high count of suppressed duplicates
- A list has been maintained manually or imported repeatedly
- Data hygiene issues are affecting segmentation or personalisation
- You want each email address to appear only once within a particular list
Tip: If you're unsure which version of a duplicate to keep, compare the field values carefully. One record often contains more complete or fresher data than the others.
Prevent duplicates at the source: Work from Audience Center Contacts as your central hub. Managing contacts and segments there means you rarely have to clean this up in the first place.
Delete duplicate records in a list
- Go to Lists > Marketing Lists, or open a list under Other Lists (for example, Form Submissions or Webinar Lists).
- On the right side of the list row, open the menu and select Maintenance > Delete Duplicates.
- A report appears showing every email address with multiple records. Click an email address to review its duplicates.
- Decide whether to keep more than one version or pick the single record you want to preserve.
- Click the red Delete icon at the top of the page to remove the unwanted records.
Best practices
- Use All Contacts for long-term list management so duplicates don't accumulate in the first place.
- Before deleting, compare each duplicate's field values so you keep the record with the most complete data.
- If duplicates keep coming back, check your import process or CRM sync settings - the problem is probably upstream.
Next steps
- The Contact Report: review every record tied to an email address.
- Searching for a Contact: find any contact versions that appear across lists.
- Audience Center Contacts: consolidate contact management to prevent future duplicates.