How to Add Subscribers to an Existing List

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You can add subscribers to an existing list by either uploading new contacts or by using Quick Add, as detailed in the sections below.

Before adding contacts using either of these methods, turn flows triggered by the list to manual. Once the import is complete, wait a few hours and then set the flow back to live.

Add Subscribers via Upload

To add subscribers to an existing list, first, navigate to the list.

Next, click the Manage List dropdown in the upper right-hand corner and select Import Contacts.


You will see two options here: Upload file and Upload via copy/paste.

Upload File

Note that, when you upload a CSV to a list that triggers a flow, the flow will be sent to everyone once they are uploaded. If you do not want this to occur, set your flow to manual. After the import is complete, wait a few hours before going back into the flow and deleting the people who you do not want to receive the email. Then, switch the flow back to live.

Select Upload file. Then, drag & drop your CSV file or select it from your computer.


Learn more about formatting your CSV file.

Before your file is uploaded, you'll be asked to review your import. The import review screen allows you to map the columns in your uploaded CSV to Klaviyo fields. The Klaviyo fields represent where your data is stored on your contact's profile.


Here, if you don't have GDPR consent fields already stored in your CSV, we can create them for you. To do this, click Add GDPR specific consent. You will be prompted to specify the types of consent the contacts on your list have given. This information will then be stored on their profile as custom properties

If you're uploading Klaviyo-specific fields, the data type is already selected for you and you're unable to modify it. If you're uploading custom properties, select the field you'd like to map the properties to and select the data type. You can also add a new custom property by typing the new property name and selecting Create option.


When you're finished mapping your Klaviyo fields, click Start Import.

Upload via Copy/Paste

Select Upload via copy/paste.

Paste contact information in this format:

Email Address First Name Last Name George Washington Abraham Lincoln

When you're finished pasting contacts, click Start Import.

Both of these options will allow you to add contacts just as you would if you were creating a new list. For instructions on how to do this, click here.

Add Subscribers via Quick Add

If you would like to quickly add a handful of individuals to your list, you can also use the Quick Add option instead. To use this option, navigate to the list you'd like to add the profile to, then click Quick Add


Note that this option is available only for lists, not segments

A few things to keep in mind:

  • Never add contacts to a subscriber list that have not intentionally opted in — this is against Klaviyo’s Terms of Service.
  • We will automatically keep customers from joining the same list more than once. This means that, if you are trying to import a file containing subscribers that are already on your list, you will notice that these duplicative records will not get added. For example, if you want to add a custom property to everyone in a list, you can safely re-upload the list with the custom property attached without creating duplicate profiles.
  • We will automatically skip email address entries that do not have a valid format. A valid email address such as is made up of a local part, an @ symbol, then a case-insensitive domain part. If any of the required parts of a valid email address are missing, we will consider the email invalid. If there are erroneous spaces in the email address, we will also consider the email invalid.

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