[Accounting integration]

Add postal mail to accounting and AP workflows

Use QuickBooks or Xero context for invoice follow-ups, tax correspondence, engagement letters, and payment-plan mailings, then keep mailed proof plus forwarded IRS, state, or client paperwork tied to the accounting workflow.

recommended shape

invoice overdue or notice approved

packet drafted from accounting context

dry_run=true preview

controller or partner approves

proof tied to the client record

Best for

Accounting firms and AP teams that still need paper correspondence.

Invoice, tax, bill, vendor, and client workflows where delivery proof matters.

Teams that need one place to connect outbound mail with inbound mailed notices, scanned replies, or supporting document packets.

Triggers

Invoice remains unpaid after a threshold.

Tax notice or client packet is approved for mail.

Vendor or customer correspondence requires certified delivery.

[Workflow]

1

Accounting app, export, webhook, or agent supplies invoice, vendor, client, or notice context.

2

Packet is drafted and previewed with mailbox.bot dry_run=true.

3

Controller, partner, or client approves sensitive mail.

4

mailbox.bot sends and tracks the piece.

5

Webhook status, proof, and any forwarded inbound tax or client documents are stored back in the accounting workflow or client record.

Technical pattern

QuickBooks Online webhooks (Invoice entity) or Xero webhooks fire when an invoice ages past the threshold.

Read the customer's billing address from the invoice record; store invoice_id and customer_id in metadata.

Write mail_id and proof back as an attachment or note on the invoice.

Route inbound tax and client notices to the engagement with keyword rules on the client or agency name.

Metadata to preserve

source=quickbooks_xero

invoice_id

customer_id

vendor_id

notice_id

approval_id

POST/api/v1/maildry_run=true

curl -X POST https://mailbox.bot/api/v1/mail \
  -H "Authorization: Bearer sk_agent_test_..." \
  -H "X-Mailbox-MD-Version: <version>" \
  -H "X-Max-Cost-Cents: 2500" \
  -F "document=@payment-reminder.pdf" \
  -F "recipient_name=<recipient>" \
  -F "recipient_line1=<street>" \
  -F "recipient_city=<city>" \
  -F "recipient_state=<state>" \
  -F "recipient_zip=<zip>" \
  -F "mail_class=certified" \
  -F "dry_run=true" \
  -F 'metadata[invoice_id]=<invoice_id>' \
  -F 'metadata[customer_id]=<customer_id>' \
  -F 'metadata[vendor_id]=<vendor_id>' \
  -F 'metadata[source]=quickbooks-xero'

Agent prompts

"When an invoice is 45 days overdue, draft a mailed payment reminder through mailbox.bot and require approval."

"Turn this tax notice reply packet into a certified mail dry run with proof metadata tied to the client record."