imaplib ... understanding the result from a fetch of RFC822s

[Jp Calderone]

On Wed, 17 Nov 2004 21:26:35 +0100, Max M <maxm at mxm.dk> wrote:
>I am using the fetch command from the imaplib to fetch messages. I get a 
> result, but I am a bit uncertain as to how I should interpret it.
> 
> The result is described at http://pydoc.org/2.3/imaplib.html as::
> 
> (typ, [data, ...]) = <instance>.fetch(message_set, message_parts)
> 
> In RFC 2060 it says: "The data items to be fetched can be either a 
> single atom or a parenthesized list."
> 
> So I do a fetch like:
> 
>      mailconn.uid('fetch', '1:*', '(RFC822)')
> 
> As a result I receive the following results (from 2 different servers):
> 
> # mailserver 1
> messages = [
>      ('1 (UID 2 RFC822 {616}', "Received: from SNIP..."),
>      ')',
>      ('2 (UID 4 RFC822 {626}', "Received: from SNIP..."),
>      ')',
> ]
> 
> # mailserver 2
> 
> messages = [
>      ('1 (RFC822 {1155}', "Return-path: SNIP..."),
>      ' UID 1)',
>      ('2 (RFC822 {977}', "Return-path: SNIP..."),
>      ' UID 2)',
>      ('3 (RFC822 {1016}', "Return-path: SNIP..."),
>      ' UID 3)',
>      ('4 (RFC822 {1153}', "Return-path: SNIP..."),
>      ' UID 4)',
>      ('5 (RFC822 {732}', 'Mime-Version: SNIP...'),
>      ' UID 5)',
> ]
> 
> It's just a long list which seems to have the structure:
> 
> list = [
>      (envelope start, rfc288-message), envelope-end,
>      (envelope start, rfc288-message), envelope-end,
>      (envelope start, rfc288-message), envelope-end,
> ]
> 
> To me this is an odd format. It's sort of a parenthesized list, but not 
> really.
> 
> I guess that I can iterate it like:
> 
> for ((envelopeStart, msg), envelopeEnd) in range(0, len(messages), 2):
>      # do stuff
> 
> But I feel a bit uncertain that it won't break in some edge cases.
> 
> Does anybody have a clue as to why imaplib returns results like that?
> 

  Parsing IMAP4 is rather involved.  imaplib does a minimal job of it, and leaves many of the details up to you.  For a more complete parser, see Twisted's IMAP4 support: http://www.twistedmatrix.com/

  Jp