IMO it's misleading to call it an email client when it does not do actual email. Making your Gmail client also-an-Outlook-client does not make it an email client.
I have a fairly non standard use of email, so I'm a bad target for brain picking. I can give a summary, though.
I work generally using a simplified GTD. Important features which I already have are good integration with my calendar and todoist as well as keyboard only navigation. Email analysis features I'd like to have are classification of:
- messages where my action is required;
- message classification by project;
- how long will it take me to handle this message (i.e. do it now vs add to todoist)
IMO it's misleading to call it an email client when it does not do actual email. Making your Gmail client also-an-Outlook-client does not make it an email client.