Bulk Create Custom Subscriber Fields in Sender From a Excel workbook

The Scenario

You're a marketing ops engineer and you've just been handed a new Sender account to set up for an upcoming product launch. The subscriber import is scheduled for next week, but before a single contact can be added, the custom field schema has to exist in Sender — otherwise every import row with a custom value will error.

You have an Excel workbook with 12 field definitions: field name in column A, field type in column B. Someone on the product team built the list based on the CRM export spec. Your job is to get all 12 fields created in Sender before the import team starts their work Monday morning.

The bad version:

• Log into Sender, navigate to custom fields, click "Add field," type in the first field name, select the type from a dropdown, save — repeat 11 more times.
• Mistype "company_sze" instead of "company_size" on field six, not notice until the import throws an error three days later, and have to delete and recreate it.
• Get through all 12 fields and realize you never wrote down the resulting field IDs, which the import team needs for the column mapping config.

Twelve fields sounds manageable until you're on field nine and realize you've been doing this for 25 minutes.

The Easy Way: One Prompt in SheetXAI

SheetXAI is an AI agent that lives inside your Excel workbook. It reads your field definition table, calls the Sender custom fields API for each row, creates the field with the correct name and type, and writes the resulting field ID — or the error — back into column C.

Create a new Sender custom field for each row in this Excel table (field name in column A, type in column B) and record the resulting field ID in column C.

SheetXAI creates each field in sequence, passes the correct type string, and logs the outcome. When it's done, column C has a row-by-row record of what was created and what failed — and if a field with that name already existed, Sender's response tells you that too.

What You Get

• Each field definition in the workbook becomes a real custom field in Sender.
• Column C fills with the resulting field ID for each successful creation.
• Rows that error — invalid type string, field name already exists, API limit — get the specific error message in column C.
• The import team has the field IDs they need without any additional manual steps.

What If the Data Is Not Quite Ready

The field type values in column B use freeform descriptions instead of Sender's API type strings

For each row, normalize the field type in column B to the nearest valid Sender custom field type ("text", "number", "date", "checkbox"), then create each field in Sender with the name from column A and the normalized type, writing the outcome into column C.

Some field names in column A have spaces or special characters that Sender doesn't accept as slugs

For each row, convert the field name in column A to lowercase snake_case to use as the field slug, then create the custom field in Sender with that slug and the type from column B, writing the slug used and the outcome into columns C and D.

You want to also verify which fields already exist before creating new ones

For each field name in column A, check whether a custom field with that name already exists in Sender and write "exists" or "not found" in column C — then create a new field only for rows marked "not found," writing the result into column D.

The full kill chain — normalize names, skip duplicates, create new fields, and write a handoff summary for the import team

For each row in columns A and B, normalize the field name to lowercase snake_case, check whether it already exists in Sender, and create it with the type from column B only if it doesn't — writing the slug, "created" or "already exists," and any error into columns C, D, and E. After processing all rows, write a summary into cell G1: total fields checked, newly created, already existed, and failed.

One prompt produces the full schema setup plus the handoff report. The import team has everything they need without a separate Slack thread.

Try It

Get the 7-day free trial of SheetXAI and open the Excel workbook with your custom field definitions, then ask it to create all 12 fields in Sender and log the field IDs before the import team arrives Monday. See also: Bulk import subscribers into Sender and the Sender integration hub.