This is what I'd like to be able to configure.
Configure sendmail as a pass-through smtp server to my yahoo smtp server. All emails sent through sendmail would go through yahoo to email addresses specified in the alias file. Also, most importantly, all emails would appear to come from firstname.lastname@example.org
no matter what/who sent them on my system.
i.e.: if I send an email to user bob on my system by 'mail -v bob' it would send an email to an alias, email@example.com
instead of firstname.lastname@example.org
ldomain and the 'from:' would say email@example.com
instead of firstname.lastname@example.org