P.S. - List Owner - your list software is set to reply to the original sender rather than the list address - in case you weren't aware of it.
I think they did this on purpose, so that there is less mail for the list to handle, but then again its annoying because you got to edit what email adress to send it to :).
As with your MySQL it being bigger, i have seen this as well. Might be because it has to include all the MySQL connection and database queries, thus making it bigger, as functions like get_pass() (NOTE: JUST AN EXAMPLE, NOT TAKEN FROM SOURCE CODE) have not to be rewritten so they work with MySQL.