Let kk.txt a file with your data.
Run this code like perl program.pl kk.txt

#!/usr/bin/perl -l

use warnings;
use strict;

undef $/;
my $txt = <>;

(my $number) = $txt =~ /mailbox (\d{11})/;
(my $from)   = $txt =~ /From: (.*?)\n/;

print "$number -> $from\n";
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