To be able to forward an email from Outlook into a Channel in a Microsoft Team is a great feature. It can be used to inform the team members of the content of an email you have received from an external user. Once forwarded into a proper channel the team members can view it and start a chat about it.
However, before you start to use this functionality too frequently, you should be aware of that there are some limitations.
In the article “Send an email to a channel in Teams” you can see how it works and also the limitations.