Not, imho, really enough info, but I'd guess that you might want (for uppercase first char):

sub build_main_email_field {
  my ($self, $name, $value) = @_;
  $name = ucfirst $name;
  return ("$name: ", $value);
}
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Bold will depend on where you are displaying the value - if html, then (although not really bold):

$name = '<em>' . $name . '</em>';
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