We've had numerous people try to install exim/postfix/whatever only to get the error message: !!! Error: the virtual/mta package conflicts with this package and both can't be installed on the same system together. Perhaps we might add what the virtual/foo package resolves to in the error message, along with something along the lines of "Run 'emerge unmerge virtual/mta' to remove whatever-virtual/foo-resolves-to, then 'emerge desired-package'".
