Smart product selection in welcome email automation

[Redroot_Blades]

Hi there, 

I have a newsletter sign up option on the website that offers a one-time discount code. It sends the code via a marketing email automation. In the email builder in Shopify, I can manually add products to display in the final email. 

The problem is that my inventory is always changing. So the email can have links to sold out items or even to an item that isn't listed at all anymore. 

Question: Can I add a dynamic function in the email builder that would always select the newest items to populate the email, or the items that are already automatically sorted as first in a collection, or ones that are not sold out specifically? 

LMK if you need more info from me. It would be a nice feature even with an inventory that doesn't sell out. 

Seems like I'd need to add a block of "custom liquid" to the email, rather than use the "add products" option in the email builder.

Thanks! 

Dustin 

redrootblades.com