still getting the same error ...

If by "... the same error ..." you mean
    Can't exec "/usr/bin/mailx uuencode $zipfile $zipfile -r -s": No such file or directory at ...
then you haven't read and/or understood poj's reply.

Use double-quotes to interpolate the  $zipfile string into the  $emailcmd string:

c:\@Work\Perl\monks>perl -wMstrict -le
"my $home = $ENV{'HOME'};
 print qq{>$home<};
 ;;
 my $zipfile = qq{$home/file.zip};
 print qq{>>$zipfile<<};
 ;;
 my $emailcmd = qq{/usr/bin/mailx uuencode $zipfile $zipfile -r -s};
 print qq{>>>$emailcmd<<<};
"
>IsWhereTheHeartIs<
>>IsWhereTheHeartIs/file.zip<<
>>>/usr/bin/mailx uuencode IsWhereTheHeartIs/file.zip IsWhereTheHeartI
+s/file.zip -r -s<<<
[download]

Maybe see discussion of  qq// et al and interpolation in perlop. (Basic problem is with string interpolation and not with existence of a file.)