use Module LIST;

##</code><code>##

require Module;
Module->import LIST if Module->can('import');

##</code><code>##

test1.pl:2     use strict;
test1.pl:4     use lib qq{/usr/web/wonko/test/lib/SYS};
test1.pl:5     use lib qq{/usr/web/wonko/test/lib/AB};
test1.pl:7     require SYS_mail;

   Start executing SYS_mail.pm

SYS_mail.pm:1  package SYS_mail;
SYS_mail.pm:3  use lib qq{/usr/web/wonko/test/lib/AB};
SYS_mail.pm:5  require AB_prod;

   Start executing AB_prod.pm

AB_prod.pm:1   package AB_prod;
AB_prod.pm:3   use lib qq{/usr/web/wonko/test/lib/SYS};
AB_prod.pm:5   require SYS_mail;

   Does nothing. Already required

AB_prod.pm:5   SYS_mail->import(qw ( send_mail ))
                  if SYS_mail->can('import');

   ERROR!!

##</code><code>##

use vars qw(@ISA @EXPORT_OK);
use Exporter();
@ISA = qw(Exporter);
@EXPORT_OK = qw( send_notice );

##</code><code>##

/usr/web/wonko/test/AB/AB_prod.pm
#--------------------------------------------------------------------
package AB_prod;

use lib qq{/usr/web/wonko/test/lib/SYS};

use strict;
use warnings;

BEGIN {
   our @ISA = qw( Exporter );
   our @EXPORT_OK = qw( send_notice );
   require Exporter;
}

use SYS_mail qw ( send_mail );

sub send_notice
{
   print qq{Hello from AB_prod::send_notice\n};

   send_mail();
}
1;
#--------------------------------------------------------------------

##</code><code>##

/usr/web/wonko/test/lib/SYS/SYS_mail.pm
#--------------------------------------------------------------------
package SYS_mail;

use lib qq{/usr/web/wonko/test/lib/AB};

use strict;
use warnings;

BEGIN {
   our @ISA = qw( Exporter );
   our @EXPORT_OK = qw( send_mail );
   require Exporter;
}

use AB_prod qw( send_notice );

sub send_mail
{
   print qq{Hello from SYS_mail::send_mail\n};
}
1;
#--------------------------------------------------------------------

##</code><code>##

use strict;
use warnings;

use SYS_mail qw( send_mail );
use AB_prod qw( send_notice );

send_notice();

__END__
output
======
Hello from AB_prod::send_notice
Hello from SYS_mail::send_mail