We have the same issue here, and it is liable to make the management team choose a different CRM if I am honest.
Desperate for a fix or workaround for this!
My current potential workaround is to inject crucial information such as unbound deal information into the contact record using existing APIs
“Hi [contact name] you created these deals: [XXXX,XXXX,XXXX] within the last 60 days but did not complete sales process”
Another suggestion which has been made by external advisor here is to use the transactional email functionality, but imo this is tantamount to us sending the email from the API application itself…
https://developers.hubspot.com/docs/methods/email/transactional_email
https://developers.hubspot.com/docs/methods/email/transactional_email/single-send-overview
There is also at least one thread on this on the dev pages as well so hopefully it makes its way in soon!