Importing contacts
This guide explains how to prepare, format, and import your contact data from a previous email platform into Sender, including how to map custom fields, assign groups, and handle suppression records.
Before You Start
- Completed initial subscriber import in Sender (basic list uploaded)
- Verified sending domain in Sender
- Admin access to your source platform to export contact lists, custom fields, tags, and suppression records
- A documented inventory of all contact data to migrate — including field names, field types, tag structures, and subscriber statuses
- Custom fields created in Sender that match your source platform's data structure (go to Subscribers → Fields → Create new field before importing)
- Groups created in Sender to correspond with your source platform's lists, audiences, or tag-based segments (go to Subscribers → Groups → Create new group)
Audit Your Source Platform
Contact fields — Document every field attached to your contacts in your source platform, including field names, data types (text, date, number, dropdown), and example values. In Sender, these map to Fields under Subscribers → Fields, where the default fields are Email, Phone number, First name, Last name, and Birthday.
Tags and lists — Record all tags, lists, or audience categories applied to contacts in your source platform. In Sender, tags and lists map to Groups under Subscribers → Groups. If your source platform uses tags for individual attributes rather than audience segments, map those to custom Fields instead.
Subscriber statuses — Identify contacts marked as unsubscribed, bounced, or marked as spam complaints in your source platform. These must be imported separately in Sender with the correct status to prevent sending to opted-out contacts.
Custom field types — Note the data type of each custom field in your source platform. Sender supports five field types: Text, Date (YYYY-MM-DD), Datetime, Number, and Drop-down. Map each source field to the closest Sender type and note any values that need reformatting before import.
Steps to Import Contacts
Step 1 — Export and prepare your contact file
In your source platform, export your full contact list as a .csv or .xlsx file. Include all fields you plan to migrate — email address, first name, last name, phone number, custom fields, tags, and subscriber status. Ensure the first row contains column headers. Remove duplicate rows and contacts with invalid email addresses. If your source platform stores tags as a column, keep that column in the file for reference during group assignment.
Step 2 — Create custom fields and groups in Sender
Before uploading your file, go to Subscribers → Fields and click Create new field for each custom field from your source platform that does not already exist in Sender. Select the appropriate field type (Text, Date, Datetime, Number, or Drop-down). Then go to Subscribers → Groups and click Create new group for each list, audience, or tag category you need to replicate. This ensures all fields and groups are available during the import mapping step.
Step 3 — Upload and map columns
Go to Subscribers → Add subscribers. On the Import subscribers page, select Import from a file. Drag and drop your file or click Import file. Sender displays the Match the columns screen with a preview of your data. Use the dropdown on each column header to assign the correct Sender field — choose from E-mail, Phone number, First name, Last name, Birthday, or any custom field you created. Select Create a new field to add a field on the fly, or Skip this column to exclude data you do not need. Verify the preview row matches your expected data.
Step 4 — Assign groups and start the import
Below the column mapping section, find Add subscribers to a group. Click the Choose groups dropdown and select one or more groups to assign the imported contacts to. You can also select Create a new group directly from this dropdown. Once fields are mapped and groups are assigned, click Start import. Sender processes the file and displays how many subscribers will be imported.
Step 5 — Import suppression records separately
Export unsubscribed, bounced, and spam-complaint contacts from your source platform as a separate file. In Sender, go to Subscribers → Add subscribers → Import from a file and upload this file. During the Match the columns step, map the email column to E-mail. After import, update the status of these contacts to Unsubscribed to prevent sending to opted-out addresses. Repeat this process for bounced contacts if your source platform tracks them separately.
Mapping Reference
Source platform contact fields → Sender Fields — Standard fields like email, first name, and last name map directly to Sender's default fields. Custom fields (e.g., company name, city, membership tier) must be created in Subscribers → Fields before import. Choose the Sender field type that matches the source data: use Text for free-form values, Date for dates in YYYY-MM-DD format, Number for numeric-only values, and Drop-down for fixed option sets.
Source platform lists or audiences → Sender Groups — Each list or audience in your source platform corresponds to a Group in Sender. Create groups under Subscribers → Groups before importing, then assign contacts during the import step using the Choose groups dropdown.
Source platform tags → Sender Groups or Custom Fields — If tags represent audience segments (e.g., "VIP", "Newsletter"), map them to Groups. If tags represent individual attributes (e.g., "Lead source: Webinar"), create a custom Field and include the tag value as a column in your import file.
Source platform subscriber status → Sender subscriber status — Active contacts import with an active status by default. Unsubscribed contacts must be imported separately and their status set to Unsubscribed to maintain compliance. Sender tracks Active, Unsubscribed, and Bounced statuses per group.
Source platform date fields → Sender Date field — Sender accepts dates in YYYY-MM-DD or YYYY-MM-DD hh:mm:ss format. Convert any date values in your export file to this format before uploading to avoid mapping errors.
What Cannot Be Migrated Automatically
Subscriber engagement history — Open rates, click data, and engagement scores from your source platform do not transfer. Sender begins tracking engagement from the first send after import.
Tag-to-contact associations as a single import action — If a contact belongs to multiple tags in your source platform, you cannot import all tag assignments in one file upload. Import contacts into one group at a time, or restructure tags as custom field values in a single column.
Subscriber status in bulk during import — Sender does not provide a status column mapping during import. Active contacts import as active by default. Suppression records (unsubscribed, bounced) must be handled separately by importing those contacts and updating their status afterward.
Source platform automation enrollment data — Information about which automations a contact was enrolled in, or their position in an automation sequence, cannot be transferred. Contacts will need to enter Sender automations from the beginning based on new triggers.
How to Test the Migration
Verify contact count — After import, go to Subscribers and compare the total subscriber count to the number of rows in your export file (minus the header row). The count displayed at 1 – X of X in the subscriber list should match your expected total.
Check field mapping accuracy — Open several individual subscriber records in Subscribers and confirm that first name, last name, phone number, and custom field values appear in the correct columns. Click Toggle fields to display additional columns if needed.
Confirm group assignment — Go to Subscribers → Groups and verify that the Total count for each group matches the number of contacts you intended to assign. Click View on a group to spot-check individual subscribers.
Validate suppression records — Go to Subscribers and use the Email status filter to check for contacts with an Unsubscribed status. Confirm that contacts from your suppression list are correctly marked and excluded from active counts.
Test a small batch first — Before importing your full list, upload a file with 5–10 test contacts. Complete the entire mapping and group assignment flow, verify the results, then delete the test contacts and proceed with the full import.
Migration Tips
Split large files — If your export exceeds 64MB, split it into multiple smaller files and import them in batches. Remove unnecessary columns to reduce file size.
Standardize date formats before upload — Convert all date values to YYYY-MM-DD format in your spreadsheet application before importing. Sender's Date field type rejects values in other formats.
Import active and suppressed contacts separately — Upload your active contact list first, then import your suppression list as a separate file. This prevents opted-out contacts from receiving emails before their status is updated.
Use the CSV template — On the Import subscribers page, click Download CSV template or Download Excel template to get a pre-formatted file. Paste your contact data into the template to ensure correct column structure.
Document your field mapping — Before starting, create a reference table that maps each source platform field name to the corresponding Sender field name and type. This prevents mapping errors during import and serves as a reference for future imports.
Common Issues
Columns not auto-detected → Column headers in your file do not match Sender's default field names exactly. Use the dropdown on each column in the Match the columns step to manually assign the correct Sender field, or rename your file headers to match Sender's defaults (e.g., Email address, First name, Last name).
Custom field missing from the dropdown → The custom field was not created in Sender before starting the import. Go to Subscribers → Fields → Create new field, create the field with the correct type, then restart the import process.
Date values not importing correctly → Date values in your file are not in YYYY-MM-DD or YYYY-MM-DD hh:mm:ss format. Open your file in a spreadsheet editor, reformat the date column, save, and re-upload.
Duplicate contacts after import → Sender identifies duplicates by email address. If duplicates appear, check your source file for rows with identical email addresses. Sender updates existing subscriber records rather than creating duplicates when the email address already exists.
Suppressed contacts appear as active → Unsubscribed or bounced contacts were imported without updating their status. Go to Subscribers, locate the affected contacts, and manually change their status to Unsubscribed, or re-import the suppression list and update statuses.
FAQs
Can I import contacts from multiple source platforms at once? Each import must use a single file. If you are migrating from multiple platforms, export each platform's contacts as a separate file, then upload them one at a time in Sender. Assign each batch to the appropriate groups during import.
What file formats does Sender accept for import? Sender accepts .csv, .txt, and .xlsx (MS Excel) files. The maximum file size is 64MB. If your file is larger, split it into smaller batches before uploading.
Can I create custom fields during the import process? Yes. On the Match the columns screen, click the column header dropdown and select Create a new field. However, creating fields in advance under Subscribers → Fields gives you more control over the field type and naming.
How do I assign imported contacts to multiple groups? On the Import subscribers page, after mapping columns, use the Choose groups dropdown under Add subscribers to a group. Select multiple groups from the list. All imported contacts from that file will be assigned to every selected group.
Will importing contacts trigger automations? Imported contacts may trigger automations that use subscriber-based triggers such as "Subscriber joins a group." Review your active automations in Automations before importing to avoid unintended sends. Pause automations temporarily if needed, then reactivate them after the import is complete.
How do I handle contacts that exist in both my source platform and Sender? Sender matches contacts by email address. If an imported contact's email already exists in Sender, the existing record is updated with the new field values from the import file rather than creating a duplicate entry.