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GoBD Compliance for Email Archiving#

This documentation applies to Piler enterprise edition 2.1.0+

Revision #1

Publication date: 2026-JAN-05

Legal notice

This documentation describes how piler enterprise supports compliance with the German GoBD requirements from a technical and organizational perspective.

It does not constitute legal advice and does not replace the organization's obligation to assess its own legal requirements, risks, and compliance measures.

Organizations remain solely responsible for:

  • determining which emails are tax-relevant or commercially relevant,
  • configuring appropriate retention periods,
  • ensuring proper access controls and audit trails,
  • maintaining overall compliance with German tax and commercial law.

piler enterprise provides technical means to support, but not substitute, regulatory and legal decision-making.

What is GoBD?#

GoBD (Grundsätze zur ordnungsmäßigen Führung und Aufbewahrung von Büchern, Aufzeichnungen und Unterlagen in elektronischer Form sowie zum Datenzugriff) is a German administrative regulation issued by the Federal Ministry of Finance.

It defines requirements for:

  • Electronic bookkeeping and record-keeping
  • Retention of tax-relevant documents in electronic form
  • Data access rights for tax authorities during audits

GoBD applies to all businesses subject to German tax law, regardless of size. Non-compliance can result in:

  • Rejection of bookkeeping by tax authorities
  • Estimated tax assessments
  • Fines and penalties
  • Increased audit scrutiny

The GoBD requirements are derived from several German laws:

Law Requirement
§ 147 AO (Abgabenordnung) Retention of tax-relevant documents
§ 257 HGB (Handelsgesetzbuch) Retention of commercial correspondence
§ 14b UStG Retention of invoices for VAT purposes
GoBD (BMF-Schreiben) Technical implementation requirements

Retention periods#

Document type Retention period
Tax-relevant documents (invoices, contracts, financial records) 10 years
Commercial correspondence (offers, order confirmations, general business letters) 6 years

The retention period begins at the end of the calendar year in which the document was created or received.

Which emails must be archived?#

Under GoBD, the following email types require archiving:

Tax-relevant emails (10 years)#

  • Invoices (incoming and outgoing)
  • Invoice corrections and credit notes
  • Contracts with financial implications
  • Payment confirmations and reminders
  • Tax declarations and correspondence with tax authorities
  • Financial statements and accounting documents

Commercially relevant emails (6 years)#

  • Offers and quotations
  • Order confirmations
  • Delivery notes and shipping confirmations
  • General business correspondence
  • Customer and supplier communications with commercial significance

Emails that do NOT require archiving#

  • Private correspondence (if permitted by company policy)
  • Spam and advertising
  • Newsletters without business relevance
  • Internal informal communications without commercial significance

GoBD requirements and Piler compliance#

The following table maps GoBD requirements to Piler enterprise capabilities:

GoBD requirement Description Piler enterprise support
Unveränderbarkeit (Immutability) Documents must not be modifiable after archiving ✓ Emails encrypted at rest with AES-256; stored in original format; SHA-256 hash verification on retrieval
Vollständigkeit (Completeness) All relevant documents must be captured ✓ Automatic capture via SMTP journaling; no manual intervention required
Ordnung (Organization) Documents must be systematically organized and retrievable ✓ Full-text search; metadata indexing; folder/category organization
Zeitgerechtheit (Timeliness) Documents must be archived promptly ✓ Real-time archiving as emails are received
Nachvollziehbarkeit (Traceability) All changes must be logged and traceable ✓ Comprehensive audit logs; access tracking; SIEM integration
Maschinelle Auswertbarkeit (Machine readability) Data must be searchable and exportable ✓ Full-text search; metadata export; eDiscovery capabilities
Aufbewahrungsfristen (Retention periods) Configurable retention per document type ✓ Flexible retention policies per mailbox, domain, or category
Datenzugriff (Data access) Tax authorities must be able to access data during audits ✓ Export in standard formats; auditor role with controlled access

Technical implementation#

1. Immutability (Unveränderbarkeit)#

GoBD requires that archived documents cannot be modified, deleted, or replaced without leaving a trace.

How Piler ensures immutability:

  • Emails are stored in their original format (EML) immediately upon receipt
  • All stored emails are encrypted at rest using AES-256
  • A SHA-256 hash is calculated and stored for each message
  • Hash verification occurs on retrieval to detect any tampering
  • Audit logs record all access and administrative actions
  • Optional: Store on WORM-compatible storage (S3 Object Lock) for enhanced protection
  • Optional: TSA timestamps provide cryptographically verifiable proof of archival time

Configuration recommendation:

For maximum GoBD compliance, enable:

TSA_ENABLED=true
TSA_URL=https://freetsa.org/tsr

This provides independent timestamp verification for archived emails.

2. Completeness (Vollständigkeit)#

All tax-relevant and commercially relevant emails must be captured completely.

How Piler ensures completeness:

  • Journal transport rule on mail server captures all emails
  • SMTP-based archiving captures emails in real-time
  • Sender and recipient metadata preserved
  • Attachments archived with parent email
  • Headers preserved in full
  • No email content is modified during archiving

Recommended mail server configuration:

Configure your mail server to send a journal copy of all emails to the Piler SMTP daemon. This ensures complete capture without relying on client-side forwarding.

3. Organization and retrievability (Ordnung)#

Archived documents must be systematically organized and efficiently retrievable.

How Piler supports organization:

  • Full-text search across email bodies, subjects, and attachments
  • Metadata search by sender, recipient, date range, size
  • Category/folder system for manual classification
  • Attachment type filtering (PDF, Office documents, etc.)
  • Saved searches for recurring queries
  • Tag system for custom classification

Search capabilities for tax audits:

Search type Capability
Date range Find all emails within a specific period
Sender/recipient Find all correspondence with a specific party
Keyword Full-text search across content and attachments
Attachment type Find all invoices (PDF), contracts (DOCX), etc.
Combined queries Complex searches combining multiple criteria

4. Traceability (Nachvollziehbarkeit)#

All processing and access to archived documents must be logged.

Piler audit logging includes:

  • Authentication events: Login attempts (successful and failed), logout, session management
  • Access events: Which user viewed which email, when, from which IP address
  • Search events: What searches were performed and by whom
  • Export events: What data was exported and by whom
  • Administrative events: Configuration changes, user management, policy changes
  • Deletion events: If permitted, what was deleted and by whom (with approval workflow)

Audit log protection:

  • Audit logs are stored separately from email content
  • Logs can be forwarded to external SIEM systems (Splunk, Sumo Logic, Syslog)
  • External log storage prevents tampering by local administrators

5. Machine readability (Maschinelle Auswertbarkeit)#

Tax authorities may request data in machine-readable formats during audits.

Piler export capabilities:

Format Use case
EML Original email format; standard and portable
MBOX Multiple emails in single file; Unix standard
PDF Printed representation with metadata
CSV Metadata export for spreadsheet analysis
PST Microsoft Outlook format (via third-party conversion)

GDPdU/GoBD data access:

For tax audits, Piler supports:

  • Z1 access: Direct system access for auditors (via auditor role)
  • Z2 access: Indirect access through reports and exports
  • Z3 access: Data carrier provision (export to external media)

The auditor role in Piler provides controlled read-only access to archived emails without modification capabilities.

6. Retention period management#

GoBD requires retention of 6 or 10 years depending on document type.

Piler retention features:

  • Retention policies configurable per domain, mailbox, or category
  • Automated purging after retention period expires
  • Legal hold prevents deletion even after retention period
  • Retention reports show what will be deleted and when

Recommended configuration:

# Default retention for commercial correspondence
RETENTION_DAYS_DEFAULT=2192  # 6 years

# Extended retention for invoices/financial documents
# Configure per category or mailbox as needed

Important: Ensure invoices and tax-relevant documents are categorized for 10-year retention, while general correspondence uses 6-year retention.

2025 GoBD amendment: E-invoicing requirements#

As of January 2025, Germany mandates e-invoicing for B2B transactions. The July 2025 GoBD amendment clarifies archiving requirements:

Key requirements#

Requirement Description Piler support
Original format retention E-invoices must be stored in the format received ✓ Emails stored in original EML format with attachments
XML preservation For structured invoices (ZUGFeRD, XRechnung), XML component is legally binding ✓ Attachments preserved in original format
No format conversion required If PDF can be generated from XML, separate PDF storage not required ✓ Original attachments always preserved
Hybrid format handling ZUGFeRD invoices contain both PDF and embedded XML ✓ Full attachment preservation

Piler automatically complies with e-invoicing requirements because:

  • All email attachments are stored in their original format
  • No conversion or modification occurs during archiving
  • XML, PDF, and hybrid formats are all preserved as received

Procedural documentation (Verfahrensdokumentation)#

GoBD requires organizations to maintain procedural documentation describing their archiving system. This documentation must cover:

Required elements#

  1. System description
  2. Software used (Piler enterprise)
  3. Hardware infrastructure

  4. Storage locations and backup procedures

  5. Process description

  6. How emails are captured (journal transport rules)
  7. How emails are classified (automatic vs. manual)
  8. How retention periods are applied

  9. How access is controlled

  10. Internal control system (IKS)

  11. Access control procedures
  12. Audit log monitoring
  13. Regular compliance reviews

  14. Incident response procedures

  15. User documentation

  16. Training materials
  17. Operating procedures
  18. Responsibility assignments

Piler can support your procedural documentation by providing:

  • System configuration exports
  • Audit log reports
  • User and role configuration reports
  • Retention policy documentation

Deployment recommendations for GoBD compliance#

Minimum requirements#

  1. Enable comprehensive archiving
  2. Configure journal transport rule on mail server

  3. Ensure all incoming and outgoing emails are captured

  4. Configure retention policies

  5. 10 years for invoices and financial documents

  6. 6 years for general commercial correspondence

  7. Enable audit logging

  8. All access must be logged

  9. Forward logs to external SIEM for tamper protection

  10. Restrict deletion capabilities

  11. Only authorized roles (e.g., auditor, compliance officer) should be able to delete

  12. Deletion should require approval workflow

  13. Regular backups

  14. Follow 3-2-1 backup rule
  15. Test restore procedures regularly

Enhanced compliance#

For organizations requiring highest assurance:

  1. Enable TSA timestamps
  2. Cryptographic proof of archival time

  3. Independent third-party verification

  4. Use WORM storage

  5. S3 Object Lock or equivalent

  6. Physical immutability at storage level

  7. External audit log storage

  8. SIEM integration (Splunk, Sumo Logic)

  9. Prevents local administrator tampering

  10. Annual compliance audits

  11. Review configuration against GoBD requirements
  12. Update procedural documentation

Auditor access for tax inspections#

During tax audits, authorities may request access to archived emails. Piler supports this through the auditor role:

Auditor role capabilities#

Capability Description
Search all emails Full access to archived content within defined scope
View emails Read email content and attachments
Export emails Download emails in standard formats
View audit logs Review access history
No modification Cannot delete, modify, or alter archived content

Creating auditor access for tax inspection#

  1. Create a user account with auditor role
  2. Define scope (date range, domains, mailboxes)
  3. Provide credentials to tax authority representative
  4. Monitor access via audit logs
  5. Disable account after audit completion

All auditor access is fully logged for accountability.

Summary: GoBD compliance checklist#

Requirement Implementation Status
Immutability AES-256 encryption, SHA-256 hashes, audit logs ✓ Built-in
Completeness Journal transport rule, SMTP archiving ✓ Configuration required
Organization Full-text search, metadata indexing, categories ✓ Built-in
Timeliness Real-time archiving ✓ Built-in
Traceability Comprehensive audit logging, SIEM integration ✓ Built-in
Machine readability EML, MBOX, CSV, PDF export ✓ Built-in
Retention periods Configurable retention policies, automated purging ✓ Configuration required
Data access Auditor role, controlled exports ✓ Built-in
Procedural documentation Customer responsibility, Piler provides supporting data ○ Customer task

Legend: ✓ = Supported, ○ = Customer responsibility

References#