My name is Daniel and I work in digital marketing at SeerBit a B2B payment fintech company.
Our team have earlier tried to find out if it was possible to track the rate of email deliveries to recipients' inboxes and found out that this feature doesn't exist on Hubpsot. One of Hubspot's support personnel let us know this and explained in details the reasons why this feature does not exist.
We would like to request that the development team at Hubspot consider building this feature as soon as possible in order for us to be able track this important metric in our email marketing operations.
Looking forward to seeing this new development that would support the improvement of our email marketing activities.