Apparently its valid syntax

$ perl -MO=Deparse,-p -e " my ${host_mail} = qq[80.80.80.80];
(my $host_mail = '80.80.80.80');
-e syntax OK
[download]

Though I'm sure many would consider it as bad as this nonsense

$ perl -MO=Deparse,-p -e " my $                     host_mail = qq[80.
+80.80.80];  "
(my $host_mail = '80.80.80.80');
-e syntax OK
[download]

Don't write code like that, its obfuscated