Trying to find an answer as well. Does the code live in Easypost or Odoo? If in Odoo where and how do you place it?

From easypost I can see to bill duties/taxes back to sender you use this code:
"options": {
"incoterm": "DDP",
}

For third party I found this.

options: {
payment: {
type: "THIRD_PARTY",
account: "123456789",
country: "US",
postal_code: "84123"
}
duty_payment_account: "123456789",
incoterm: "DDP"
}

Question is does this have to pushed from Odoo to Easypost or can this be configured in Easypost?

Has anyone made any headway on this? I've sent a request into to Easypost to see if they can shed light on it, would love any advice for implementing this

No headway made into this. I spoke with my Odoo rep recently & asked them to offer a built in app solution for Easypost or FedEx similar to how UPS is well integrated.

I also spoke with an Odoo partner who could setup the API integration, but that would require me to migrate my database to Odoo.sh instead of the Odoo Online option.

I see that this appears to be a relevant issue still.

Easypost API definitely supports receiver and third-party billing.

If helpful and viable for some, Steersman Co in Chicago had its Easypost integration since before it was available as a standard app in Odoo, and developed some advanced features onto it over time.

* Shipping paid by shipper, receiver, or third party (allows specifying account)
* Delivery method specified on SO, and propagates into delivery (can be modified on delivery)
* Delivery method and billing type can be set on Customer and populates into new SO's
* Rate shopping enabled across multiple specific carriers and service levels. For example, can rate shop USPS Priority, UPS Ground, UPS SurePost, FedEx Ground and UPS 2nd Day Air with a condition to pick cheapest rate as long as package is reported to arrive within 2 days.
* Multiple package sizes per shipping method for estimates (to enable estimates with small or large boxes or multiple boxes, based on weight)
* Estimates can have a margin (+/- %) and a markup (+/- specific dollar amount)
* Shipping method availability can be filtered by total order amount AND net order weight

Some config screenshots:
https://drive.google.com/file/d/1-vkinbzP3YsRN7ZPKmtE77upuF53FzFm/view?usp=sharing
https://drive.google.com/file/d/1rQM6IAYUD0TFfWQCkMgFliDN1XZBrpxW/view?usp=sharing
https://drive.google.com/file/d/1LAPmagWcC9Up23Ws3EksDhuE7Kq2K5Qj/view?usp=sharing

There are a few "however" things:

The app doesn't support the creation of return labels as Odoo's own app does. The module is only supplied to customers on Steersman's ERP cloud subscription. Not compatible with Odoo's default online store app.

Can check out how estimates work here: https://legionsafety.com/ (its one of the Odoo sites with our front-end tech).

Thanks Andrey -- you guys have a nice customized solution there with proper EasyPost Integration. Maybe you can license that to Odoo for their enterprise edition? If I wasn't 3 years in on the out-of-the-box platform, I'd consider migrating.

@joe, Thanks, its been long in the making, and since we work closely with clients - had to build stuff that works well in a real environment.

To be honest, well over half of our clients switched to working with us After implementing Odoo with somebody else (or after trying to do so for some time).

We've thought about the idea of trying to provide some of our bigger apps to Odoo so they offer them in the master Odoo system, I even messaged Fabrice (Odoo Americas director) about it, but I guess there wasn't any interest. We've built also a big PIM, image processing, TaxJar integration, pricing automation, product compatibility management, etc. So we just offer them on our own subscription hosting.