Why not just use Email::Simple like you've already been pointed at? Please don't ask the same question multiple times.

my %hash;
open FH, "<", "/path/to/file" or die "Can't open file: $!";
while(<FH>) {
   chomp;
   if($_ =~ m/^([^:]+): (.*)$/) {
      $hash{$1} = $2;
   }
}
close FH;
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You mean, other than using Email::Simple?

#!/usr/bin/perl
use strict; use warnings;

open my FILE, '<', $ARGV[0] or die "Can't read $ARGV[0]: $!";

my %header;
while (<FILE>) {
   chomp; # trim trailing newline
   my ($k, $v) = split(': ', $_, 2);
   $header{$k} = $v;
}

# now $header{To} eq 'san<sanjay@36.212.176.07>' &etc.
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You don't want a regex. You want split.

Have you really tried running any code on your own? What have you tried? If you did try the snippet I provided earlier, and had trouble with it, why didn't you post a reply there? Be explicit and clear about what you tried: the actual script, the actual input data, the actual output data, how that actually fell short of your intentions.

Please give some relevant feedback to the suggestions you've been given, so we can help you move forward.

One major flaw in your concept will be exposed by files which contain "To:" more than once: Perl hash keys must be unique, which means that the hash's value will be overwritten each time "To:" shows up.

Unless this is a rather bizarre (and poorly specified) homework assignment (it isn't, is it?), you should:

1. Do a supersearch here, and search on CPAN for ways to parse email. You've had several pointers; follow them and pay attention.
2. Be more forthcoming with the context of what you're trying to do. There are monks with expertise in just about all programming-related disciplines; there is a very good chance one has solved a remarkably similar problem.

When you are handling text, I would recommend that you use regular expressions instead of commands like slice. Slice will be more appropriate when working with arrays

Below is the code using regex for what you requested.

#Assuming that you pass the file name as a parameter when executing th
+e script.
my %table;
open (F1, "<$ARGV[0]") || die ("Can't open the file $ARGV[0]. $!\n");
while(<F1>) {
    chomp;
    if($_ =~ /([^:]+): ([^\n]+)/) {
        $table{$1} = $2;
    }
}
close F1;
#printing the table.
for (keys %table)
{
    print "$_\t$table{$_}\n";
}
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Using regex, I am picking two parts of the string. The first part of the string until a colon is encountered and the second part after the colon followed by a word space until a carriage return is encountered.

Great. And then he's going to try and use this to parse an RFC822 mail header which has continuation lines in it and it's going to miss parts of a header and then he'll be back here asking the same frelling question another time.