Lua

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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Lua

local chilkat = require("chilkat")

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

local email = chilkat.Email.new()
email.subject = "Header field enumeration"
email.from = "mary@example.com"
email:add_to("Joe", "joe@example.com")

local n = email.num_header_fields
print("NumHeaderFields = " .. n)

for i = 0, n - 1 do
    print(email:get_header_field_name(i) .. ": " .. email:get_header_field_value(i))
end