Mark conversations as read / unread

We get a lot of sales- and support-related emails and I cannot believe that such an essential and important feature doesn’t exist, along with adding tags for example..

As a sales user of Hubspot I would like to filter my emails on:
1. Read/Unread (now emails get read automatically when viewing them), I want to keep them unread to follow up next day.
2. Important/not important by adding tags to conversations. Why isn’t there an option to add custom tags? Such as Important/Not Important, Product X, etc. I know converting a conversation to a deal gives more options, but in our case we have 10 request and maybe 1 will convert into a deal.

3. Display the tags on emails in the conversation overview, so it’s easy to cherry-pick the most important conversations.
We’re coming from Helpscout but also used Zendesk in the past for incoming messages, you can learn a lot from these tools. Much more user friendly and better UX for handling conversations.