How to Skip Leads If Email Already Exists in Google Sheets (Prevent Duplicates)

[hassan133]

Hi everyone,

I’m working on a simple automation but running into a logic issue, and I’d really appreciate some help.

My Use Case

I have a workflow in n8n that processes incoming leads (name, company, email, etc.). I want to check if the lead’s email already exists in my Google Sheets CRM, and then:

• If the email exists, I want to skip the lead (do nothing)
• If the email does not exist, I want to continue processing (add to the sheet, send an email, etc.)

What I’ve Tried

I used the Google Sheets “Lookup” node to search by email. The issue is that when the email does not exist, it returns nothing ([]), which makes it hard to filter properly in the next IF node.

In the IF node, I want to create a condition that says:

• If no match is found → proceed
• If a match is found → skip

But I can’t figure out the right expression or setup to check for an empty result from Google Sheets.

My Setup:

• My Google Sheet has a column called Email
• I use “Lookup Spreadsheet Row” node, searching by Email
• Leads come from an earlier node (AI-generated or webhook input)
• I’m stuck on how to structure the IF node correctly after the lookup

What I Need Help With:

• How to write the correct condition in the IF node to detect if the email was not found in the sheet
• Any best practices for preventing duplicates like this in Google Sheets

Thanks in advance!
Really appreciate any help or node examples if possible.

[jack_cui]

Hello
In “if” node,you can use contains “@” to as true,so when the result is ,it will go to false node.

[fahmiiireza]

Hi there, you can do an if like this

so it checks if the previous node is empty, then if it is, it turns to true which on your case, if its empty, it means that the email are not duplicated or does not exist yet in the sheet

make sure that your previous sheet has the settings always output data turned on

if it helps you, please give this answer a like and mark it as the solution

[fahmiiireza]

hi there, if i help solve your question please mark my answer as the solution @hassan133