I would like to propose the inclusion of a mail use flag for this package, making it possible to remove the dependency on virtual/mta. Looking at the configure options for sudo: --without-sendmail appears to disable dependence on a mail program being installed. I also suggest that this be disabled by default, because an unobservant server admin could install sudo and not realize a mail relay program was also installed. It may however, most likely preferable to enable the flag by default, to keep the existing behavior.
Created attachment 334134 [details, diff] Add USE=mail
It appears this has been implemented completely independently of this ticket since it was created. I am marking this as resolved. http://sources.gentoo.org/cgi-bin/viewvc.cgi/gentoo-x86/app-admin/sudo/sudo-1.8.6_p8.ebuild?revision=1.2&view=markup