Sending an invoice by email: What are the rules and specificities?

Key points to remember:

• Validity of an invoice by email: An invoice sent by email is legally valid in France if its authenticity, integrity, and readability are guaranteed.
• Writing the invoicing email: An invoicing email should be professional, mention the subject of the invoice, the amount due and the due date, and end with an availability statement.
• File format: An invoice sent by email is usually in PDF or Factur-X format, the latter becoming mandatory in France from September 1, 2026.
• Invoice receipt: After sending an invoice by email, it is recommended to check its proper receipt by the client to avoid any processing or payment delay.

Do you want to send an invoice by email to your client? Today, invoicing is governed by strict laws and concerns all French companies. As a result, invoicing by email requires certain best practices to avoid disputes and ensure efficient and secure transmission. This is why Weepo reveals the rules and specificities for sending an invoice by email: from legal validity to the invoicing email, with a focus on electronic invoicing.

Invoice by email: Is it legally valid?

Sending an invoice by email is perfectly legal and legally recognized in France. The validity of an invoice sent by email must, however, meet the following 3 conditions:

1. Authenticity of origin: The sender’s identity must be clearly established.
2. Content integrity: The invoice must not be modified after its issuance.
3. Content readability: The document must be easily readable by all relevant parties (service provider, client, accountant, etc.).

An invoice sent by email must also contain the same mandatory statements as a paper invoice.

💡Good to know: You have the option of using a certified electronic signature to strengthen the authenticity and integrity of the invoice.

How to write the invoicing email?

The invoicing email must remain polite and professional. It should never contain informal phrases. As for the structure, start your email by addressing your client directly, then remind them of the invoice subject, the amount due, the due date, and remember to conclude with a reassuring sentence like: "I remain at your disposal for any further information". As for the subject of the email, it should clearly reflect its content. For example, you can include: "Invoice No. X from company (Y) for (such purchase or service) dated (XX/XX/XXXX)".

Don’t forget to include your contact details and the logo of your company in the email signature.

📌Sample invoicing email:
Subject: Invoice No. 458 – Durand Info Company – IT Maintenance Service on 05/03/2026

Dear Sir or Madam,

Please find attached invoice No. 458 for the IT maintenance service performed on March 5, 2026.

The total amount due is €850 including tax. This invoice is payable no later than April 4, 2026, in accordance with the agreed upon payment terms.

Thank you for your attention to this payment and for the trust you place in our company.

I remain at your disposal for any further information and ask you to accept, Madam, Sir, the assurance of my highest regards.

[Name and surname][Position][Company][Contact details]

How to send an invoice by email?

To send an invoice by email, you have two options:

1. Write the email yourself;
2. Opt for invoicing software.

With the second option, you benefit from an invoicing module integrated into your software, with all mandatory information pre-filled. This means no more errors or omissions! The transmission of the invoice to your client is usually done in three clicks, and you can monitor payment deadlines directly via the interface. Most accounting tools also offer the option to schedule automatic reminders. To choose the best tool, check out our comparative guide to invoicing software.

Wage portage: a solution to delegate invoicing

Faced with the different options for sending an invoice by email, some freelancers prefer to choose wage portage and delegate all their administrative management. With this option, the issuance of invoices, their compliance, and all legal obligations are fully handled by the umbrella company. As a wage portage consultant, you no longer have to worry about formats, mandatory information, or regulatory changes such as electronic invoicing.

💡Good to know: Specialized companies like Weepo particularly support IT and digital freelancers by simplifying their daily admin while allowing them to focus on their core business.

Which file format for an invoice by email?

The format of your invoice must be readable so that it can be easily integrated into your client's accounting systems. Two formats are possible:

1. PDF format: The most common, it ensures that the layout is preserved when opening the file.
2. Factur-X format: It combines a readable PDF and structured XML data to facilitate automated accounting processing.

💡Good to know: The Factur-X format will be mandatory in France from September 1, 2026. Anticipating this requirement now is a very good idea.

Verifying the receipt of the invoice by the client

After sending, always remember to verify that the invoice was received by your client. To do this, you can set a read or delivery receipt request, or add a specific mention at the end of your email such as: "please confirm the proper receipt of this invoice". If you do not receive any confirmation within a few days, follow up with your client by email or by phone. This will help avoid any processing delay.

What are the benefits of invoicing by email?

Sending an invoice by email has several significant advantages:

Benefit	Explanation
Time savings	Sending an invoice by email eliminates the need to travel and allows for almost immediate delivery to the client. This speed accelerates invoice processing and can reduce payment times, thus limiting risks to the company's cash flow.
Cost reduction	The digital format eliminates costs linked to paper invoicing: purchasing paper, ink, printing, envelopes, and stamps. Individually minor, these costs become significant when cumulated over a large number of invoices.
Simplified process	The invoice is received instantly in the recipient's inbox, reducing the risk of delay or loss. The document can be accessed at any time and from anywhere, facilitating faster processing and payment.

Zoom on the electronic invoicing reform

As part of the electronic invoicing reform, your invoice will now follow a predefined format. It will no longer be sent directly from the supplier to the client but will pass through an approved platform (PA). Therefore, PDF files are excluded and it will no longer be possible to send an invoice by email. To learn more, read our article on the impact of electronic invoicing for micro-entrepreneurs.

Invoice by email: what to remember

You now know all the rules and specificities of sending an invoice by email. Here is a quick summary:

1. To be legally valid, an invoice sent by email must be authentic, readable, and integral.
2. The invoicing email must remain polite, formal, and include a clear subject and message.
3. You can send your invoice either by writing your own email or by using accounting software.
4. An invoice sent by email must be in PDF or Factur-X format.
5. Invoicing by email offers considerable time savings, reduces paper-related costs, and simplifies transmission.
6. With the electronic invoicing reform, it will no longer be possible to send your invoices by email.

To learn more, read our article to learn how to draft your freelance invoice.