sensible defaults for mail folders (folder templates)

[grexe]

Now that I finally got around to fix GMail setup with app passwords and successfully downloaded my mail, I noticed again the missed opportunity with the rather useless default layout for mail folders.

The mail window will only show Name, Size and Modified columns, instead of more appropriate and useful attributes from mails like Sender, Subject and Thread.

Also, displaying the Name is redundant when there is already a mail Subject, and Modified is not needed and just a technical information when there is a When attribute that reflects better what users need to know (when the mail was sent, not when it was written to disk).

This way, newcomers and average users may never realise the power of mail the way Haiku handles it. Even if they do, it is cumbersome and unnecessary forcing users having to rearrange the layout to include sensible default columns and getting rid of unecessary ones like Name or Modified.

Filing this under Preferences/E-Mail for lack of a better fit, I think the folders are created there.