Skip to main content

Documentation Index

Fetch the complete documentation index at: https://docs.lettr.com/llms.txt

Use this file to discover all available pages before exploring further.

Importing and exporting are the two main ways to move contact data in and out of Lettr in bulk. Use import when bringing contacts in from another tool, a spreadsheet, or your own system. Use export when you want a snapshot of your audience for backup, external analysis, or migration.

​
Importing Contacts from CSV

The CSV import flow is a guided, multi-step process designed to handle messy real-world files — including ones without header rows, with mixed column orders, and with extra columns that don’t map cleanly to Lettr fields.

​
Before You Start

A bit of preparation saves time:
  • Define your custom properties first. If you want to import data like first_name, plan, or signup_date, create those properties in Audience → Properties before importing. The import flow can then map your CSV columns directly to existing properties.
  • Have your file ready. A CSV with one contact per row. The only column the import truly needs is the email address; everything else is optional.
  • Decide how you want to handle duplicates. If a contact in your CSV already exists in your audience, you can either skip them entirely or update them with the new values from the file.

​
The Import Flow

1

Upload the file

Go to Audience → Imports → New import and select your CSV. The file is uploaded directly to secure storage. There’s no hard size limit imposed by the UI, but very large files (many millions of rows) may take longer to process.
2

Map columns

Lettr reads the first few rows of your file and asks you to map each column to a Lettr field. The choices are:
  • Email — required, exactly one column
  • Status — optional; if a column contains values like subscribed or unsubscribed, you can map it here. Otherwise contacts are imported as subscribed
  • Property name — map a column to any of your defined custom properties
  • Ignore — skip the column entirely
If your CSV does not have a header row, Lettr will use AI to guess what each column represents and you can correct it before continuing.
3

Pick options

Choose how duplicate emails are handled:
  • Skip — existing contacts in your audience are left untouched. New emails are added
  • Update — existing contacts have their properties (and status, if mapped) overwritten with the CSV values
You can also attach every imported contact to one or more lists or topics in this step.
4

Start the import

Once you start the import, it runs in the background. You can leave the page; you’ll receive an email notification when it completes with a summary of how many contacts were created, updated, and skipped.

​
AI-Assisted Column Mapping

For CSVs from common sources, Lettr can suggest a complete column mapping with one click. The AI looks at the column names (or their content if there’s no header) and proposes mappings to your existing properties. You always get a chance to review and adjust before continuing.

​
What Happens After an Import

  • All imported contacts immediately appear on the Contacts page
  • Topic memberships set in the import step are applied. Opt-in topics defined for your team are also automatically attached, just as they would be for any new contact
  • Segments re-evaluate their match counts in the background
  • Contacts from the import don’t generate per-contact entries in the activity log (the import uses a faster bulk path) — but any later edits to those contacts log normally
Importing does not check your marketing plan’s contact limit. If your import would push you over your limit, the contacts will still be added, but you won’t be able to send campaigns until you upgrade your plan or remove enough contacts to fit. Check Billing for plan details.

​
Tips for Clean Imports

Even basic format validation in a spreadsheet (filtering out obviously malformed addresses) saves you from a flood of bounces later. Lettr only bulk-validates the structure of email values — it does not verify whether an inbox actually exists.
On your first import of a list, Skip prevents any unintended changes to existing contacts. On a recurring refresh (for example, syncing customer data from your CRM weekly), Update keeps property values fresh.
If your source system tracks unsubscribes, map a column to Status so those contacts come in as unsubscribed and won’t be emailed. If you don’t have status data, leave it unmapped — new contacts default to subscribed.
Large imports work, but breaking up data into chunks (per cohort, per source) makes it easier to spot mistakes before they affect your full audience.

​
Exporting Contacts to CSV

Exporting produces a CSV file of your contacts that you can download from your email. Exports respect any filters you have applied on the Contacts page, so you can export a subset of your audience without first creating a list.

​
How to Export

1

Filter your contacts (optional)

On the Contacts page, apply any filters you want — search by email, filter by status, list, topic, or segment.
2

Start the export

Open the Export menu and start the export. The job runs in the background; you don’t have to wait on the page.
3

Download the file

When the export is ready, you’ll receive an email with a download link. The link is also visible from the Recent exports panel on the Contacts page.

​
What’s in the Export

The CSV contains one row per matching contact. Columns include the email address, status, every custom property defined for your team, and the timestamps for when the contact was created and last updated.

​
Limits

  • Each user can run up to 20 exports per hour
  • Download links expire 1 hour after the export becomes ready. You can re-run the export if you need a fresh download

​
Next Steps

Contacts

Set up custom properties to populate during import

Lists

Attach imported contacts to a list

Double Opt-In

For sign-up forms, prefer double opt-in over imports