PowerBuilder

Email Received Header Fields

Received emails will contain one or more "Received" header fields at the beginning of the email header. Each SMTP server (along the delivery path) adds a Received header to the top of the incoming message. The delivery route can be ascertained by the sequence of Received headers. There is a good summary of the Received header here.

The following explanation is taken from the reference URL above:

In theory, the value of a Received field is tokenizable. It contains

    1) optionally, a "from" atom followed by an encoded domain name;
    2) optionally, a "by" atom followed by an encoded domain name;
    3) optionally, a "via" atom followed by another atom;
    4) zero or more of the following: a "with" atom followed by another atom;
    5) optionally, an "id" atom followed by either (1) an atom or (2) a < token, an encoded address, and a > token;
    6) optionally, a "for" atom followed by an encoded address;
    7) a semicolon; and
    8) a timestamp. 

In practice, SMTP servers put all sorts of badly formatted information into Received lines. It is probably best for readers to treat everything before the final semicolon as unstructured text, purely for human consumption.

This example demonstrates iterating over each of the Recevied headers and getting the content of each.

PowerBuilder

integer li_rc
integer li_Success
oleobject loo_Email
oleobject loo_SbHdrName
integer i
integer li_NumHeaders

li_Success = 0

loo_Email = create oleobject
li_rc = loo_Email.ConnectToNewObject("Chilkat.Email")
if li_rc < 0 then
    destroy loo_Email
    MessageBox("Error","Connecting to COM object failed")
    return
end if

// Load a .eml file into the email object.
li_Success = loo_Email.LoadEml("/home/users/chilkat/eml/myEml.eml")
if li_Success = 0 then
    Write-Debug loo_Email.LastErrorText
    destroy loo_Email
    return
end if

loo_SbHdrName = create oleobject
li_rc = loo_SbHdrName.ConnectToNewObject("Chilkat.StringBuilder")

i = 0
li_NumHeaders = loo_Email.NumHeaderFields
do while i < li_NumHeaders
    loo_SbHdrName.SetString(loo_Email.GetHeaderFieldName(i))
    if loo_SbHdrName.ContentsEqual("Received",0) = 1 then
        Write-Debug "Received: " + loo_Email.GetHeaderFieldValue(i)
    end if

    i = i + 1
loop


destroy loo_Email
destroy loo_SbHdrName