When new address replies create duplicates
Last updated January 15, 2026
If you're using Smartlead and receive an email reply from a new address, you may notice a seemingly duplicate lead/contact is created in your CRM.
This issue arises when a lead replies to a campaign from an email address different from the one originally enrolled in the Smartlead email campaign.
And if email address is the unique identifier, then a new email address results in a new lead/contact.
Here's why it happens and how to manage it.
Understanding the Issue
When a reply comes from a different email address than the original lead in Smartlead, OutboundSync may create two separate leads in your CRM. Here's what typically happens:
- The Email Reply event is tied to the actual email address that sent the reply.
- Other events, such as Email Sent or Lead Category Updated, remain tied to the original lead's email address.
As a result:
- One lead is created based on the Email Reply event.
- Another is created from events like Lead Category Updated.
If you are using Category Based Filters , both "leads" pass through OutboundSync's filters because they share the same lead_id and campaign_id.
The second lead may also lack a full name, if the field is not mapped in the Lead Category Updated payload.
Why This Happens
This behavior is difficult to resolve due to how Smartlead sends data via webhooks. OutboundSync associates each activity with the email address provided in the event itself, we don't receive additional context to link them otherwise.
| Original lead address | gawain@balltownboba.com | Receives Email Sent and Lead Category Updated events |
| Reply from address | gawain@rockyroadchocolate.com | Triggers an Email Reply event tied to this new address |
Without a way to automatically merge these, duplicates can occur in your CRM.
OutboundSync could forcibly merge them based on the shared lead_id and campaign_id but they could also be a different person, which would lead to a different type of data hygiene issue.
Workarounds and resolutions
While we can't prevent this entirely at the moment, here are steps to handle it:
- Pre-enrich domains before campaigns. If you add known aliases for the companies you're prospecting into, you can improve the match rate to current companies which can make de-duping easier at the company- or account-level.
- Merge duplicate contacts/leads in your CRM: Manually review and merge the leads in your CRM using built-in de-dupe tools. This consolidates the data and prevents clutter. And it ensures later events are properly synced.
- Track reply events manually: Maintain a list or report of contacts that receive reply events to spot potential duplicates early.
- Set up workflow branches: Using your native CRM automation tool, create a branch that generates a review task for reply events missing details like Last campaign name/ID, Last sent email, or Last lead category name/ID. This flags cases where the reply may came from a different address.
You cannot use a custom lead/contact object record lookup ID as an alternative, because custom fields/properties are not supported in Smartlead's webhook payloads.
Consider re-enrollment options in your campaigns to minimize mismatched replies. Remember to test changes before deploying any changes to your campaigns while they're in production.
If issues persist, contact our team for assistance .