Kentucky wrote:

For anonymous messages I say the possibility to send messages without
specify any senders for the messages, so that the recipient receive a
mail with From=blank.

Whether or not the From field is blank has no bearing on whether or not the
message is anonymous. It's whether or not the sender address and headers
are masked that truly bears upon the subject. There's no way I know in
Outlook to not have a sender address, which, if there is no From field, will
be interpreted by the recipient client as From. (I don't know of any way in
Outlook to exclude the From, either.)
--
Brian Tillman