Flexmail Python API Docs | dltHub

Build a Flexmail-to-database pipeline in Python using dlt with AI Workbench support for Claude Code, Cursor, and Codex.

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Flexmail is an email marketing and transactional email service API. The REST API base URL is https://email-api.flexmail.eu and All requests require HTTP Basic authentication using an API username and API token..

dlt is an open-source Python library that handles authentication, pagination, and schema evolution automatically. dlthub provides AI context files that enable code assistants to generate production-ready pipelines. Install with uv pip install "dlt[workspace]" and start loading Flexmail data in under 10 minutes.


What data can I load from Flexmail?

Here are some of the endpoints you can load from Flexmail:

ResourceEndpointMethodData selectorDescription
contacts/contactsGETRetrieve contact records.
lists/listsGETRetrieve contact list (address book) records.
messages/messagesGETRetrieve sent messages / mailings.
senders/sendersGETRetrieve configured sender identities.
templates/templatesGETRetrieve email templates.

How do I authenticate with the Flexmail API?

Send an Authorization header with the value "Basic <base64(username:token)>", where the username is the API username (account ID) and the token is the API token.

1. Get your credentials

  1. Log into the Flexmail dashboard.
  2. Navigate to Account Settings → API / Personal Access Tokens.
  3. Click Create new token, give it a name, and select the required scopes.
  4. Save the token; copy it immediately as it will not be shown again.
  5. Also note your API username (account ID) displayed in the same settings page.

2. Add them to .dlt/secrets.toml

[sources.flexmail_source] api_username = "your_api_username" api_token = "your_api_token"

dlt reads this automatically at runtime — never hardcode tokens in your pipeline script. For production environments, see setting up credentials with dlt for environment variable and vault-based options.


How do I set up and run the pipeline?

Set up a virtual environment and install dlt:

uv venv && source .venv/bin/activate uv pip install "dlt[workspace]"

1. Install the dlt AI Workbench:

dlt ai init --agent <your-agent> # <agent>: claude | cursor | codex

This installs project rules, a secrets management skill, appropriate ignore files, and configures the dlt MCP server for your agent. Learn more →

2. Install the rest-api-pipeline toolkit:

dlt ai toolkit rest-api-pipeline install

This loads the skills and context about dlt the agent uses to build the pipeline iteratively, efficiently, and safely. The agent uses MCP tools to inspect credentials — it never needs to read your secrets.toml directly. Learn more →

3. Start LLM-assisted coding:

Use /find-source to load data from the Flexmail API into DuckDB.

The rest-api-pipeline toolkit takes over from here — it reads relevant API documentation, presents you with options for which endpoints to load, and follows a structured workflow to scaffold, debug, and validate the pipeline step by step.

4. Run the pipeline:

python flexmail_pipeline.py

If everything is configured correctly, you'll see output like this:

Pipeline flexmail_pipeline load step completed in 0.26 seconds 1 load package(s) were loaded to destination duckdb and into dataset flexmail_data The duckdb destination used duckdb:/flexmail.duckdb location to store data Load package 1749667187.541553 is LOADED and contains no failed jobs

Inspect your pipeline and data:

dlt pipeline flexmail_pipeline show

This opens the Pipeline Dashboard where you can verify pipeline state, load metrics, schema (tables, columns, types), and query the loaded data directly.


Python pipeline example

This example loads contacts and messages from the Flexmail API into DuckDB. It mirrors the endpoint and data selector configuration from the table above:

import dlt from dlt.sources.rest_api import RESTAPIConfig, rest_api_resources @dlt.source def flexmail_source(api_username=dlt.secrets.value): config: RESTAPIConfig = { "client": { "base_url": "https://email-api.flexmail.eu", "auth": { "type": "http_basic", "password": api_username, }, }, "resources": [ {"name": "contacts", "endpoint": {"path": "contacts"}}, {"name": "messages", "endpoint": {"path": "messages"}} ], } yield from rest_api_resources(config) def get_data() -> None: pipeline = dlt.pipeline( pipeline_name="flexmail_pipeline", destination="duckdb", dataset_name="flexmail_data", ) load_info = pipeline.run(flexmail_source()) print(load_info)

To add more endpoints, append entries from the resource table to the "resources" list using the same name, path, and data_selector pattern.


How do I query the loaded data?

Once the pipeline runs, dlt creates one table per resource. You can query with Python or SQL.

Python (pandas DataFrame):

import dlt data = dlt.pipeline("flexmail_pipeline").dataset() sessions_df = data.contacts.df() print(sessions_df.head())

SQL (DuckDB example):

SELECT * FROM flexmail_data.contacts LIMIT 10;

In a marimo or Jupyter notebook:

import dlt data = dlt.pipeline("flexmail_pipeline").dataset() data.contacts.df().head()

See how to explore your data in marimo Notebooks and how to query your data in Python with dataset.


What destinations can I load Flexmail data to?

dlt supports loading into any of these destinations — only the destination parameter changes:

DestinationExample value
DuckDB (local, default)"duckdb"
PostgreSQL"postgres"
BigQuery"bigquery"
Snowflake"snowflake"
Redshift"redshift"
Databricks"databricks"
Filesystem (S3, GCS, Azure)"filesystem"

Change the destination in dlt.pipeline(destination="snowflake") and add credentials in .dlt/secrets.toml. See the full destinations list.


Troubleshooting

Authentication Errors

  • 401 Unauthorized – Occurs when the HTTP Basic credentials are missing, malformed, or invalid. Verify that the apiUsername and apiToken are correct and that they are base64‑encoded in the Authorization header.

Rate Limiting

  • 429 Too Many Requests – The API throttles excessive calls. Respect the Retry-After header and implement exponential back‑off.

Pagination

  • The API uses standard page and pageSize query parameters. If a response contains a nextPage link, follow it to retrieve subsequent records.

Ensure that the API key is valid to avoid 401 Unauthorized errors. Also, verify endpoint paths and parameters to avoid 404 Not Found errors.


Next steps

Continue your data engineering journey with the other toolkits of the dltHub AI Workbench:

  • data-exploration — Build custom notebooks, charts, and dashboards for deeper analysis with marimo notebooks.
  • dlthub-runtime — Deploy, schedule, and monitor your pipeline in production.
dlt ai toolkit data-exploration install dlt ai toolkit dlthub-runtime install

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