When you submit a subscriber list directly to Attentive for upload, your file must meet specific formatting requirements before we can process it. This article covers the certification step, required file format, and the most common mistakes to avoid.
What is it?
Subscriber List Upload Requirements is the set of file format and process rules you must follow when submitting a subscriber list to Attentive for upload. It covers required and optional fields, phone number formatting, date formatting, and file preparation rules that determine whether your list uploads successfully or gets flagged with invalid records.
How do I use it?
Step 1: Complete certification
- Before uploading, your team must submit the Subscriber List Certification form.
- The file will be uploaded exactly as provided. Attentive will not edit, reformat, or otherwise adjust the file. Please confirm that the file is complete and formatted correctly before uploading. If you're unsure whether your file meets these requirements, reach out to your Attentive contact before uploading.
Step 2: Prepare your file
- File type: CSV (.csv) only. Do not upload Excel files (.xlsx).
- One subscriber per row, with a header row of column names.
- Include only opted-in, active subscribers — remove unsubscribed users before uploading.
- Plain text only: no cell colors, formulas, merged cells, or extra sheets/tabs.
Step 3: Format required and optional fields by subscription type
- Text - create subscriber
- Phone number:
- US and Canada: any common format is accepted — parentheses, dashes, or a leading +1 (e.g., (555) 123-4567, 555-123-4567, +15551234567).
- All other countries: phone numbers must be in E.164 format — a plus sign followed by country code and number, no spaces, brackets, or dashes (e.g., +44XXXXXXXXXX for the UK, +61XXXXXXXXX for Australia).
- Optional fields: email, first name, last name, signup date, and other subscriber attributes as needed.
- Phone number:
- Email - create subscriber
- Valid email address
- Update attribute
- Requires at least one identifier
- Phone number
- Email address
- Push token
- Client ID
- Shopify ID
- Klaviyo ID
- SFMC ID
- Cordial customer ID
- Click ID
- Requires at least one identifier
Step 4: Format dates and data types
- Dates must use yyyy-mm-dd (example: 2026-04-15).
- These date formats are not accepted and will cause records to be marked invalid:
- mmm-dd-yyyy (example: Jan-20-2021)
- mm-dd-yyyy (example: 01-20-2021)
- mmm-yyyy (example: Jan 2021)
- Accepted boolean values:
- true: "true", "yes", "on", "y", "t", "1"
- false: "false", "no", "off", "n", "f", "0"
- During upload, select the correct field type per column — Date for dates, String for text. The wrong type marks the attribute as invalid and will not ingest them.
Step 5: Upload and notify us
- Upload your file to the Box folder shared with your team.
- Email your Attentive contact to confirm the upload.
- Common mistakes to avoid
- Uploading an Excel file instead of CSV
- Using a non-E.164 format for international numbers (e.g., 07911 123456 instead of +447911123456)
- Multiple phone numbers in one cell
- Including unsubscribed users
- Applying formatting (colors, formulas, merged cells)
- Adding extra sheets or tabs
If you're unsure whether your file meets these requirements, reach out to your Attentive contact before uploading.
Why should I use it?
Following this format the first time helps your list upload correctly on the first attempt. Files that don't meet these requirements can fail to upload, produce invalid subscriber records, or require Attentive's team to manually reformat your data — all of which delay onboarding and campaign launch.