This is the best I could come up with. I can't find anyway except for looping through the messages.

Also make sure to import the in method, because it isn't imported by default.

#! /usr/bin/perl

use strict;
use warnings;

use Win32::OLE qw( in );

#Outlook Application creation
my $outlook = Win32::OLE->CreateObject('Outlook.Application');
my $ns = $outlook->getNamespace('MAPI');
my $inbox = $ns->GetDefaultFolder(6);

#String to match
my $match_str = 'test';

#Search the items
foreach my $item (in $inbox->Items){
    if($item->{Subject} =~ /^$match_str/i){
        print "$item->{Subject} matches\n";
    }
}
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