I don't think there exist an autotag feature, but you can use template expansions [1] to put the sender's name as a tag in the headline. For instance, you could use the template expansions "%:from", "%:fromname" or "%:fromaddress". But I don't know how this will play if you also use the template expansion that prompt for tags.
[1] http://orgmode.org/manual/Template-expansion.html#Template-expansion -- Darlan
