Perl

Enumerate the Header Fields of an Email

Demonstrates the read-only Chilkat Email.NumHeaderFields property together with GetHeaderFieldName and GetHeaderFieldValue to enumerate every header field. Indexing is zero-based, so fields run from 0 to NumHeaderFields - 1. Repeated header fields (a field name that appears more than once) are counted separately. This example builds a small email and prints each header field.

Background: A header field is a single Name: value line at the top of a MIME message. The same field name can legitimately appear multiple times — for example, a message can carry several Received lines, one added by each mail server it passed through. That is why enumerating by index (rather than looking up by name) matters: it lets you see every occurrence in the order it appears.

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Chilkat2 Perl

use strict;
use warnings;
use Chilkat2;

# Demonstrates the read-only Email.NumHeaderFields property and enumerating each
# header field by zero-based index using GetHeaderFieldName and GetHeaderFieldValue.

my $email = Chilkat2::Email->new;
$email->Subject('Header field enumeration');
$email->From('mary@example.com');
$email->AddTo('Joe', 'joe@example.com');

my $n = $email->NumHeaderFields;
print 'NumHeaderFields = ', $n, "\n";

for my $i (0 .. $n - 1) {
    print $email->GetHeaderFieldName($i), ': ', $email->GetHeaderFieldValue($i), "\n";
}