If the allnet option is checked and the metoo option is not checked, and you do a Reply to All, your address is not included in any form in the To or Cc fields of your reply.
For example, suppose you receive a message with this header:
From: salmon@sea Fri Aug 23 10:36:21 1991 To: yourname@machine, yourname@host, tuna@ocean
The To field of your reply would look like this:
To: tuna@ocean, salmon@sea