store sent mail and incoming mail in one group?

[Xiao-Yong Jin]

Somehow, I want my mail group to be managed more or less like the way
news groups do.  That is I can see my mails in sort of subject in one
group where both my incoming mails and sent-out mails are listed.

Does it mean what I only need is to put the sent mails in the same
group with my incoming mail?  And how?