Know which overdue Dynamics SL customers email can still reach

**Objective:** List Dynamics SL customers whose current balance is at least `{min-balance}` (default 1000) and check, for each, whether their email address is reachable in Constant Contact, so collections outreach does not go to dead or unsubscribed addresses.

**Step 1: Customers with a balance**

Call `dynamics-sl-get-customer-balances` with `current-balance.min` = `{min-balance}` and `max-records` 100. Keep `customer-id`, `customer-name`, `current-balance`, the age-balance buckets and `average-days-to-pay`. Sort by the oldest non-zero bucket, then by balance.

**Step 2: Get each customer's email**

The balances list carries no email, so call `dynamics-sl-get-customers` with each `customer-id` and take `email-address` and `phone-number`.

**Step 3: Check the address in Constant Contact**

For each email, call `constant-contact-get-contact` with it as `email-address`. When a contact is found, call `constant-contact-get-campaign-bounce` and `constant-contact-get-campaign-unsubscribe` with its `contact-id` and `created-date.from` 180 days ago.

**Step 4: Report**

A table sorted by risk: customer id, customer name, balance, oldest overdue bucket, email, and an **Email status** column of one of: Reachable, Bounced (with bounce type), Unsubscribed, Not in Constant Contact, No email on file. Finish with a short list of customers to contact by phone instead, with the SL phone number.

**Rules & Guidelines:**

* dynamics-sl tools: `dynamics-sl-get-customer-balances`, `dynamics-sl-get-customers`. constant-contact tools: `constant-contact-get-contact`, `constant-contact-get-campaign-bounce`, `constant-contact-get-campaign-unsubscribe`.
* Read-only. Do not call `constant-contact-add-contact-note`, `constant-contact-update-contact`, `constant-contact-add-campaign` or any other write tool.
* An unsubscribed contact has opted out of marketing email; say so, and do not suggest emailing them a campaign.
* If the user has named a Dynamics SL company, pass it as `company` on every dynamics-sl call.

**Validation:**

* If no customer meets the balance threshold, say so and stop.
* A hard bounce outranks an unsubscribe in the status column.