How can I save an email as html with attachments? (html file with index) For me, it is very useful to save your email easily! For example, Thunderbird can do that via ImportExportTools NG add on!
You can’t.
What you can do is save the messages as an eml file. This is the complete message contained in the file, including attachments, and can be opened by any email client.
You will find this by right-click and Save As.