How to Manage Duplicate Contacts

Duplicate contacts occur when the same email address appears more than once in your Mailzzy account, or when the same person exists under two slightly different records. Left unmanaged, duplicates inflate your contact count, cause the same person to receive multiple copies of a campaign, and can skew your engagement data. This guide explains how to identify, prevent, and resolve duplicate contacts.

Why Duplicates Occur

Duplicates most commonly appear as a result of:

• Multiple CSV imports where the same addresses were present across different files

• Manual contact additions made without checking whether the address already exists

• Contacts signing up through a form more than once using the same email address

• Importing contacts from different data sources that share some overlap — for example, a CRM export and a separate event sign-up list

• Slight variations in how the same person’s name is recorded across imports

How Mailzzy Handles Duplicate Email Addresses

Mailzzy uses the email address as the unique identifier for each contact record. When you import a CSV that contains an email address already present in your account, Mailzzy will typically update the existing record with any new data from the import rather than creating a second record for the same address.

This means true duplicates — identical email addresses appearing twice — are largely prevented by the import process. However, issues can arise when:

• The same person has signed up with two different email addresses (e.g., a personal and a work address)

• An address was manually entered with a typo and the correct version was later added separately

• Contacts were imported to different groups without checking for overlap first

How to Find Potential Duplicates

1. Go to the Contacts page.
2. Use the search bar to search for a name, company, or other identifying information that might surface multiple records for the same person.
3. Review the results for contacts who appear to be the same individual under different records.
4. Compare the email addresses, names, and tags on each record to confirm.

How to Resolve a Duplicate

Mailzzy does not currently offer an automated duplicate merge tool. When you identify a duplicate, the recommended approach is:

1. Decide which of the two records is the primary one — typically the one with the most complete data or the most recent activity.
2. Open the secondary (duplicate) record and note any data, tags, or group memberships that are not present on the primary record.
3. Add any missing tags or groups to the primary record manually.
4. Delete the secondary record. See How to Delete Contacts for instructions.

Preventing Duplicates During Imports

The most effective way to manage duplicates is to prevent them from appearing in the first place:

• Before importing a new list, remove any email addresses from the CSV that you already know are in your account

• Use a spreadsheet tool to run a deduplication check on your CSV file before uploading — most spreadsheet applications include a “Remove Duplicates” function

• When importing contacts from multiple sources that may overlap, import one source first, then review the list before adding the second

• If you are collecting sign-ups through a form, Mailzzy will update an existing contact record rather than creating a new one when the same address is submitted again

What to Do About Contacts with Multiple Email Addresses

If the same person genuinely uses two different email addresses — such as a work address and a personal address — both may legitimately exist as separate contacts. In this case, tagging both records with a shared identifier — such as the person’s company or a “Duplicate Person” tag — can help you manage them consciously rather than accidentally sending the same campaign to both addresses.