Skip to content
Rechnungskit

Sending invoices through your own AhaSend account

Updated

AhaSend is an email sending service based in the Netherlands, and your data stays in the EU. With the delivery method "AhaSend", Rechnungskit sends your invoices through your own AhaSend account. The emails come from an address on your domain, and you don't need a mail server of your own. Rechnungskit talks to AhaSend's API directly.

Why AhaSend

  • We use it ourselves. Since 15 October 2026, all of Rechnungskit's emails go through AhaSend, including the "Rechnungskit delivery" method.
  • Data in the EU. AhaSend B.V. is based in the Netherlands and stores all message data in the EU.
  • Affordable. The first 1,000 emails a month are free.
  • Built for sending from software. Gmail and Outlook mailboxes often have sending limits and need app passwords. AhaSend is made for emails from applications like Rechnungskit.

Setting it up

  1. Create an account with AhaSend. Referral link: we earn a commission, nothing changes for you.

  2. Add your domain in AhaSend and set the DNS records AhaSend shows you. You can send once AhaSend lists the domain as verified.

  3. In AhaSend, create an API key with only the messages:send permission for your domain. Set the sending mode to "Production". A key in "Sandbox" mode accepts every email but delivers nothing, so your invoices would look sent and never arrive. You'll find the account ID in the AhaSend dashboard.

  4. In Rechnungskit, open Settings → Email delivery, choose "AhaSend" and enter the account ID, API key and sender address.

    Rechnungskit, Settings → Email delivery: under the delivery methods, "AhaSend" with the label "EU, recommended" is selected and highlighted, with "Own SMTP" above and "Rechnungskit delivery" below. Underneath are the three setup steps: create an AhaSend account, add your domain and set the DNS records, create an API key with the messages:send permission in sending mode "Production"

  5. Click "Test connection", then save.

    Rechnungskit, Settings → Email delivery with AhaSend: account ID and API key are filled in, the sender address is rechnung@nordlicht-kaffee.de. Below are the reply-to field and the preview: from Nordlicht Kaffee GmbH <rechnung@nordlicht-kaffee.de>, reply to buchhaltung@nordlicht-kaffee.de, the subject line, the email text with company details and the invoice PDF attached

Good to know

  • The sender address must be on your verified domain. For example, enter invoices@your-company.com if your-company.com is verified in AhaSend. If the address is on a different domain, AhaSend rejects the send. Your company name appears as the sender name.
  • The key stays secret. Rechnungskit stores the API key encrypted and never shows it again after saving. Leave the field empty to keep the saved key. If you change the account ID, Rechnungskit asks for the key again.
  • The test delivers nothing. "Test connection" and the check on saving send a message in AhaSend's sandbox mode. AhaSend checks the key, permission and domain as it would for a real send, but delivers nothing and charges nothing. For a real test email, tick "Send a real test mail to …" before testing. It goes to the contact address in your company details.
  • You'll see delivery problems in your AhaSend dashboard. If an invoice bounces, AhaSend shows it there. With your own account, these reports don't reach Rechnungskit. Anything AhaSend rejects at send time shows up on the invoice and as a task in Rechnungskit.

Error messages and what they mean

Message in Rechnungskit What's behind it What to do
The API key is invalid or has been deleted. AhaSend doesn't know the key (HTTP 401) Create a new key in AhaSend and enter it
AhaSend rejects the send The domain isn't verified, or the key lacks the messages:send permission for it (HTTP 403) Verify the domain in AhaSend, check the key's permission, use a sender address on that domain
AhaSend could not be reached. No response, or an error at AhaSend Wait a moment and send again
AhaSend rejected the recipient address. AhaSend won't accept the address, for example after an earlier hard bounce Check the customer's email address

Where to find it in the app

Rechnungskit is not a tax advisory or law firm. This article explains general principles and does not replace advice from a tax advisor (Steuerberater, § 5 StBerG) or a lawyer (§ 3 RDG). Rechnungskit is built for businesses based in Germany and prepares documents, tax rates and bookings automatically. How your specific case is treated remains your decision, ideally together with your tax advisor or a lawyer.

de en