# BR-DE-7 Seller contact email must be provided

The seller contact group must contain an email address.

## Problem Description

The seller contact group must contain an email address.

> **ERROR**: XRechnung 3.0

## Context and Significance

This entry follows the XRechnung 3.0.2 Schematron rule semantics used by KoSIT validation.

## Solution

Fill BT-43 seller contact email address.

- validate
- convert

## Valid Examples

- BT-43 Seller contact email address is present and valid.

## Invalid Examples

- BT-43 Seller contact email address is missing or invalid.

## Technical Details

### Affected Fields
BT-43 Seller contact email address

## Related Rules

- [BR-DE-2](/resources/kosit-validator-errors/br-de-2-seller-contact-required)
- [BR-DE-28](/resources/kosit-validator-errors/br-de-28-seller-email-should-be-shaped-like-email)

## Validation Tools

- [Official KoSIT Validator](https://erechnungsvalidator.service-bw.de/): Validate your XRechnung files against all BR-DE rules.
- [Convert PDF to XRechnung](/pdf-to-xrechnung): Automatic validation error fixes when converting.

## Related Resources

- [Official Specification](https://xeinkauf.de/xrechnung/)
- [Test Suite](https://github.com/itplr-kosit/xrechnung-testsuite)
- [Complete Error List](/resources/kosit-validator-errors): Overview of all German XRechnung validation rules.