my $AID = "XD4555";

my $query = $dbh->prepare("SELECT 
snd.EMAIL FROM 
FUSERS as m 
JOIN USERS as snd ON snd.USERID = m.USERID WHERE (m.USERID_IM = ?)");
$query->execute($AID);
my $user1 = $query->fetchall_arrayref();

my $query_other = $dbh->prepare("SELECT 
snd.EMAIL FROM 
FUSERS as m 
JOIN USERS as snd ON snd.USERID = m.USERID_IM WHERE (m.USERID = ?)");
$query_other->execute($AID);
my $user2 = $query_other->fetchall_arrayref();

my $TotalEmails = $user1 + $user2;

foreach my $em ( $TotalEmails ) {
    my $rez = join( ",", $em);
	print "$rez\n";
	}