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Convert invoices by email: how the channel works
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Convert invoices by email: how the channel works

2 min readReviewed: August 29, 2026
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Official references

Use these sources to verify dates, formats, and official rule changes.

Related Technical Wiki

Explore deep-dive developer documentation and regulatory guidelines matching this article.

API and automation error messages

Common integration error codes explained for non-technical users.

Source data readiness for e-invoices

What to check before turning ERP, PDF, or spreadsheet invoice facts into structured XML.

Why invoices need review

Why human review is part of reliable invoice conversion.

The email channel converts genuine PDF invoice attachments and returns validated artifacts in the same thread. It is included with every active Enterprise subscription and suits controlled, low-volume workflows.

Setup and first conversion

Interactive flow

Press play or click a step to follow one invoice through this channel.

Output:XRechnungZUGFeRDEN16931UBLCII

Pipeline stage

Step 1 of 6YouOne-time setup

Turn on Email Import

Email Import is included with every active Enterprise subscription. Enable it in your profile; no manual approval is needed.

Email Import converts genuine PDF attachments from verified senders and replies with the validated file in the same thread. 1. Turn on Email Import: Email Import is included with every active Enterprise subscription. Enable it in your profile; no manual approval is needed. 2. Verify every sender: Only verified sender addresses are processed. Choose where replies go and in which language. 3. Email the PDF: Send one invoice PDF per email, with up to 8 supporting PDFs such as timesheets. With several PDFs, name the invoice in an Invoice file line. Up to 10 attachments, 10 MB each. The generic inbox needs exactly one format tag in the subject. Each email uses one conversion unit per format. 4. Extracted and validated: The visible PDF content is extracted and checked by the same strict conversion and validation pipeline as the API. 5. The reply arrives in the same thread: It carries the e-invoice and its HTML validation report. The service does not forward the invoice to your customer. 6. Review before you forward it: Low-confidence cases and warnings still need human review. Compare the result with the source before sending it on. Output: XRechnung, ZUGFeRD, EN16931, UBL, CII. Steps as described in this guide and the email channel documentation. Status: October 2026.
  1. Start an Enterprise subscription and switch on Email Import in your profile. No approval by our team is needed.
  2. In the account profile, add and verify every sender address. Choose the reply destination and language.
  3. Copy an inbox from the profile. The generic inbox needs exactly one subject tag such as [XRechnung], [ZUGFeRD], [EN16931], [UBL], or [CII].
  4. Send one invoice per email, attached as a genuine PDF. With supporting PDFs such as timesheets, name the invoice in an Invoice file line. Each email uses one conversion unit per format.
  5. Open the threaded reply and review the issued file plus its HTML validation report.

Important limits

Only verified senders are processed. The channel accepts genuine PDF attachments, not renamed images. Low-confidence cases and warnings still need human review. Available units must cover the full message before processing begins.

Email or API?

Use email when a person or mailbox rule benefits from a reply thread. Use the External API when a system needs idempotency, task status, rate-limit information, and explicit downloads.

Frequently asked questions

Can any sender use the address?

No. Each sender must be added and verified in the Enterprise account profile.

Does the service forward the invoice to my customer?

No. It returns results to the configured sender or collective address. You control the later delivery.

See the current email channel

Review setup, subject tags, outputs, billing, limits, and human-review rules.

Invoice import by email

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