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BR-DE-28: Seller email address (BT-43) has an invalid format

Official message

[BR-DE-28] In BT-43 soll genau ein @-Zeichen enthalten sein, welches nicht von einem Leerzeichen, einem Punkt, aber mindestens zwei Zeichen auf beiden Seiten flankiert werden soll. Ein Punkt sollte nicht am Anfang oder am Ende stehen.

XRechnung (CII) · Warning · Message language: German · Version: xrechnung-3.0.2-validator-configuration-2026-08-31

[BR-DE-28] In BT-43 soll genau ein @-Zeichen enthalten sein, welches nicht von einem Leerzeichen, einem Punkt, aber mindestens zwei Zeichen auf beiden Seiten flankiert werden soll. Ein Punkt sollte nicht am Anfang oder am Ende stehen.

XRechnung (UBL) · Warning · Message language: German · Version: xrechnung-3.0.2-validator-configuration-2026-08-31
Severity
Warning Note: this does not make the invoice invalid, but it should be checked.
Applies to
XRechnung (CII), XRechnung (UBL)
Affected fields
BT-43

What does this mean?

The email address in the seller contact details (BT-43) should contain exactly one @ sign, no spaces, and after the @ a domain name with at least one dot that is not at its beginning or end. The given address does not meet this. The message is a warning.

Typical causes

A typo, e.g. a missing @, two @ signs or a comma instead of a dot.
The address contains a space, e.g. before or after the @.
The domain part has no dot, starts or ends with a dot, or contains two consecutive dots.
The field contains several addresses or additional text, e.g. "Invoices: invoice@example.com".

How to fix the error

Enter exactly one email address in the form name@domain.com, without spaces or additions.
CII: ram:SellerTradeParty/ram:DefinedTradeContact/ram:EmailURIUniversalCommunication/ram:URIID, UBL: cac:AccountingSupplierParty/cac:Party/cac:Contact/cbc:ElectronicMail.
Generate and validate the invoice again.

In E-Rechnungsfreund

In the invoice form, section "Verkäufer (BG-4)" (seller), correct the field "E-Mail (BT-43/58)".

Example

Wrong

<ram:EmailURIUniversalCommunication>
  <ram:URIID>invoice@example</ram:URIID>
</ram:EmailURIUniversalCommunication>

Correct

<ram:EmailURIUniversalCommunication>
  <ram:URIID>invoice@example.com</ram:URIID>
</ram:EmailURIUniversalCommunication>
For developers: test expression per syntax

XRechnung (CII) (CII)

Context: /rsm:CrossIndustryInvoice/rsm:SupplyChainTradeTransaction/ram:ApplicableHeaderTradeAgreement/ram:SellerTradeParty/ram:DefinedTradeContact

matches(normalize-space(ram:EmailURIUniversalCommunication/ram:URIID), $XR-EMAIL-REGEX)

XRechnung (UBL) (UBL)

Context: /ubl:Invoice/cac:AccountingSupplierParty/cac:Party/cac:Contact | /cn:CreditNote/cac:AccountingSupplierParty/cac:Party/cac:Contact

matches(normalize-space(cbc:ElectronicMail), $XR-EMAIL-REGEX)

Related validation rules

  • BR-DE-1: Payment instructions (BG-16) are missing
  • BR-DE-10: Deliver to city (BT-77) is missing
  • BR-DE-11: Deliver to post code (BT-78) is missing
  • BR-DE-14: VAT category rate (BT-119) is missing in the VAT breakdown
  • BR-DE-15: Buyer reference (BT-10) is missing
  • BR-DE-16: Seller VAT ID, tax number or tax representative is missing

Last updated:
Explanation of the validation rule, not legal or tax advice.