Invoice Sending & Delivery#

Send invoices via email or SMS, send reminders, and get the invoice PDF and QR code.

Overview#

Multiple ways to deliver invoices to customers:

📧 Email - Branded email with the invoice PDF attached
📱 SMS - Text message with the pay link
🔗 Pay link - Every invoice has its own pay URL (shortLink, or {host}/pay/invoice/{linkId})
📄 PDF download - Direct PDF generation
📲 QR code - Scannable code for the pay link

All endpoints use the admin REST headers (Authorization: Bearer YOUR_TOKEN + X-Tenant-ID, or x-api-key).

Invoices are always delivered to the contact details stored on the invoice (customerEmail, customerPhone). To deliver to a different address, update the invoice first (Update Invoice for drafts, Edit Invoice otherwise). Message content comes from the platform templates and the merchant's branding — subject, body, CC/BCC and reply-to cannot be set per request.

Send Invoice#

Generic send: delivers by email or SMS.

Endpoint#

POST/api/v1/invoices/:invoiceId/send

Send Invoicebash

curl -X POST https://uat.auxcore.net/api/v1/invoices/0b8e6a3c-5d2f-4c71-9e1a-7f3b2c9d4e10/send \
  -H "Authorization: Bearer YOUR_TOKEN" \
  -H "X-Tenant-ID: your-tenant-id" \
  -H "Content-Type: application/json" \
  -d '{
    "method": "email",
    "to": "customer@example.com"
  }'

Parameter	Required	Description
`method`	Yes	`email` or `sms`
`to`	Yes	Must be present, but delivery always goes to the invoice's stored email / phone

Response:

Send Invoicejson

{
  "success": true,
  "data": { "message": "Invoice sent successfully" }
}

With "method": "sms" the message is "Invoice sent via SMS successfully".

Send via Email#

Emails the invoice with its PDF attached. No request body.

Endpoint#

POST/api/v1/invoices/:invoiceId/send-email

Send via Emailbash

curl -X POST https://uat.auxcore.net/api/v1/invoices/0b8e6a3c-5d2f-4c71-9e1a-7f3b2c9d4e10/send-email \
  -H "Authorization: Bearer YOUR_TOKEN" \
  -H "X-Tenant-ID: your-tenant-id"

Response: { "success": true, "data": { "message": "Invoice sent successfully" } }

Send via SMS#

Texts the pay link to the invoice's customerPhone. No request body.

Endpoint#

POST/api/v1/invoices/:invoiceId/send-sms

Send via SMSbash

curl -X POST https://uat.auxcore.net/api/v1/invoices/0b8e6a3c-5d2f-4c71-9e1a-7f3b2c9d4e10/send-sms \
  -H "Authorization: Bearer YOUR_TOKEN" \
  -H "X-Tenant-ID: your-tenant-id"

Response: { "success": true, "data": { "message": "Invoice sent via SMS successfully" } }

What sending does#

Sets the invoice status to sent and stamps sentAt — for any sendable status, including viewed, partial and overdue.
The invoice is marked sent before the email/SMS is handed off; if the hand-off fails the call returns 500 but the status and deliveryHistory entry are already saved.
Appends an entry to deliveryHistory: { "channel": "email" | "sms", "sentAt", "recipient", "actorId", "actorEmail" }.
Sending again (resend) uses the same endpoints.

Errors#

Status	When
`400`	No `customerEmail` (email) / `customerPhone` (SMS) on the invoice
`400`	Invoice is `paid`, `cancelled` or `expired` ("Cannot resend a paid, cancelled or expired invoice")
`400`	`/send` without `method` / `to`, or an unknown `method`
`404`	Invoice not found in your tenant

Send Reminder#

Send a payment reminder email now, with the PDF attached. No request body.

Endpoint#

POST/api/v1/invoices/:invoiceId/send-reminder

Send Reminderbash

curl -X POST https://uat.auxcore.net/api/v1/invoices/0b8e6a3c-5d2f-4c71-9e1a-7f3b2c9d4e10/send-reminder \
  -H "Authorization: Bearer YOUR_TOKEN" \
  -H "X-Tenant-ID: your-tenant-id"

Response: { "success": true, "data": { "message": "Reminder sent successfully" } }

Email only. Allowed for sent, viewed, partial and overdue invoices that have a customerEmail; otherwise 400. Updates reminderSentAt and reminderCount.

Get the Pay Link#

There is no separate pay-link endpoint. The invoice returned by create / get carries it:

shortLink — short URL, when the shortener minted one
linkId — the full pay URL is {host}/pay/invoice/{linkId}

A full edit rotates linkId; the old link then returns 410 LINK_ROTATED.

Generate QR Code#

Endpoint#

GET/api/v1/invoices/:invoiceId/qr-code

Generate QR Codebash

curl https://uat.auxcore.net/api/v1/invoices/0b8e6a3c-5d2f-4c71-9e1a-7f3b2c9d4e10/qr-code \
  -H "Authorization: Bearer YOUR_TOKEN" \
  -H "X-Tenant-ID: your-tenant-id"

Response: a PNG data URL encoding the pay link. There are no size / format / colour options.

Generate QR Codejson

{
  "success": true,
  "data": { "qrCode": "data:image/png;base64,iVBORw0KGgoAAAANSUhEUg..." }
}

Download PDF#

Endpoint#

GET/api/v1/invoices/:invoiceId/pdf

Download PDFbash

curl https://uat.auxcore.net/api/v1/invoices/0b8e6a3c-5d2f-4c71-9e1a-7f3b2c9d4e10/pdf \
  -H "Authorization: Bearer YOUR_TOKEN" \
  -H "X-Tenant-ID: your-tenant-id" \
  -o invoice.pdf

Returns application/pdf as an attachment.

Delivery Tracking#

Delivery is tracked on the invoice itself (GET /api/v1/invoices/:invoiceId):

Field	Description
`sentAt`	Last time the invoice was sent
`deliveryHistory`	One entry per send, with channel and recipient
`viewedAt` / `viewCount`	When / how often the customer opened the pay link (status becomes `viewed`)
`reminderSentAt` / `reminderCount`	Manual reminders

Note: provider-level delivery status (delivered, opened, bounced) is not available via API.

Webhooks#

Delivery does not emit webhooks. The only invoice event is invoice.paid (see Invoices).

Best Practices#

✅ DO:#

Check contact details before sending - delivery goes to the stored email/phone
Provide multiple options - Email + SMS increases delivery
Make payment easy - Share the pay link or QR code
Use reminders for overdue invoices

❌ DON'T:#

Don't spam - Limit resends and reminders
Don't send drafts by accident - a send moves the invoice to sent
Don't ignore bounces - Update bad email addresses with Edit Invoice

Troubleshooting#

Email Not Delivered#

Check:

Is customerEmail set and correct on the invoice?
Not in the spam folder?
Email provider blocking?

SMS Not Delivered#

Check:

Is customerPhone set on the invoice?
Is it a valid US mobile number?

Next Steps#

Need help? Contact support@auxcore.net