That happens when the new string is shorter than the old one, and is not entirely overwritten. There is, probably, a way to clear only that part of the screen before updating the label or padding the new string with spaces, but a better approach in my opinion is to use an TextEntry widget with 'readonly' and not 'focusable' attributes instead of a Label:

##########################
#####  OPTIONS PAGE  #####
##########################
my $EMAIL;
$w{2}->add(
    undef, 'Label',
    -y => -10,
    -text =>
"Please add email address here below in the event that the results wil
+l be mailed to you(Optional)\n"
);

my $temp;
my $ent1;
$w{2}->add(
    undef,
    'Buttonbox',
    -y       => -7,
    -buttons => [
        {
            -label   => " [EMAIL] ",
            -value   => 1,
            -onpress => sub {
                my $cui = shift()->root;
                $EMAIL = $cui->question("PLEASE ENTER EMAIL:");
                if ($EMAIL) {
                    $ent1->text("Address: $EMAIL");
                }
                else {
                    $cui->dialog("Question cancelled.");
                }
            },
        },
    ],
);

$ent1 = $w{2}->add(
    "ent1", "TextEntry",
    -y         => -5,
    -width     => 100,
    -readonly  => 1,
    -focusable => 0,
);
[download]

Regards, Stefan