If yahoo sends out an email from list-name@yahoo, then that is where the
email is from.
So it would be correct to set the from/sender in the email to be
list-name(_at_)yahoo(_dot_)com.
Why try to make it fake anything?
If you want to preserve any digital signature in the original message,
then send the original email as a mime body part in the forwarded message.
--
Doug Royer - (K7DMR.us / DougRoyer.com)
DouglasRoyer(_at_)gmail(_dot_)com
714-989-6135
smime.p7s
Description: S/MIME Cryptographic Signature