Before you import a file of contacts into Constant Contact, it's a good idea to make sure you have the correct file type and that the data is formatted correctly. To ensure all contacts get imported, each one needs at least an email address or an SMS phone number and consent date.
Did You Know? If you're having trouble importing your file, there are steps you can take to troubleshoot the issue. Not all errors prevent your file from being imported. After you upload a spreadsheet of contacts, you can check for errors that prevent contacts from being added to your list and correct them if you have any.
Minimum import requirements
Before importing contacts, ensure your file contains the minimum required fields based on your marketing strategy:
- Email marketing only - Each email marketing contact must have a valid email address.
- SMS marketing only - Each SMS marketing contact must have a valid SMS phone number and an SMS consent date.
- Email marketing and SMS marketing - Each contact must have either an email address or an SMS phone number with an SMS consent date. Contacts can have one or both.
Compatible file types
- Microsoft Excel (.XLS or .XLSX)
- Comma Separated Values (.CSV) - Compatible with Excel, OpenOffice Calc, and Google Sheets.
- vCard (.VCF)
- Text File (.TXT) - Created using Microsoft Notepad or similar text editors.
File size limits and restrictions
Ensure your file adheres to the following maximum size limits:
- XLS or XLSX - 25MB with 500,000 rows of data or less
- CSV - 50MB with up to 1,000,000 rows of data or less
- VCF - 2MB with 40,000 rows of data or less
- TXT - 2MB with 40,000 rows of data or less
Important: Excel spreadsheets that are larger that 25MB can cause import errors. Convert large Excel files to .CSV format or split the file into smaller files before uploading.
File naming guidelines
Special characters in file names can cause upload failures.
- Allowed in file names - Letters, numbers, and underscores.
- Prohibited Characters - Do not use spaces or characters such as -, ~, !, &, %, $, #, *, (, or ).
- Recommended naming example - Use underscores to separate words or dates, such as new_clients_2026.csv
Spreadsheet formatting rules (.XLS, .XLSX, .CSV)
Follow these formatting guidelines to prevent data processing errors:
- Row and column layout - Place header labels in the very first row. Do not leave the first row blank. Place each contact on its own individual row.
- Single data types per column - Place each piece of information in a separate column (for example, separate "First Name" and "Last Name" into two distinct columns).
- Unique column headings - Give every column a unique label. Match column headings to standard Constant Contact fields whenever possible.
- Existing tags - Create any tags in your Constant Contact account before importing. Tags included in a spreadsheet that do not already exist in the account will be ignored during import.
- Hidden rows or columns - Unhide or delete all hidden rows and columns before importing.
- Multiple worksheets - Consolidate all data into the first tab or worksheet and delete extra worksheets.
- Formulas - Convert all cells containing formulas into plain text values before saving and importing.
- Special characters and spaces - Remove extra spaces or invalid characters inside email addresses.
- SMS formatting - Ensure phone numbers and consent dates do not contain placeholder values such as "N/A" or all zeros.
Text file formatting rules (.TXT)
Follow these rules when importing a plain text file:
- Header line - Include column headers on the very first line of the file.
- Line breaks - Place each contact on a new, separate line.
- Separators - Use tabs to separate different fields on the same line. Exact visual alignment of columns is not required.
General capitalization and case sensitivity
- Case Sensitivity - Field headers, email addresses, and contact names are not case-sensitive during import.
- Text Casing - Text is imported exactly as formatted in your file. Names starting with lowercase letters will remain lowercase and will not auto-capitalize upon import.
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