Re: [Courier-imap] Courier-imap 5.0.2, pop access unicode errors

[Sam V. <mr...@co...>]

Eugene Suprun writes:

> One can download  the maildir containing only one message that leads to the  
> error, from  
> <URL:https://yadi.sk/d/oQEZZ_0LqPsFxQ>https://yadi.sk/d/oQEZZ_0LqPsFxQ . I  
> believe there is nothing wrong with the message, and I am sure there is

No problems downloading that message either:

RETR 51
+OK 231602 octets follow.
Return-Path: <g.k...@lo...>
Delivered-To: kor...@bs...
Received: from mail.bsuir.by (localhost [127.0.0.1])
	by mail.bsuir.by (Postfix) with ESMTP id 90F136C83
[ etc ]

Just to make sure that I was running the right version, with an  
intentionally-corrupted message, and without enabling UTF-8, I get the  
expected result.

RETR 85
-ERR Cannot open message 85 because it is a Unicode message and your E-mail  
reader did not enable Unicode support. Please use an E-mail reader that  
supports POP3 with UTF-8 (see https://tools.ietf.org/html/rfc6856.html)

> I "repaired" the inbox  of a user that above mentioned way: by means of an  
> imap client (roundcube webmail) deleted all his mails from inbox, then  
> brought them back to inbox, but in a couple of days the user gets another  
> message that disables again his pop3 client because of "Command RETR failed"  
> error.

There's nothing about such a particular message that should disable a POP-3  
client completely. The POP-3 client is free to continue and download the  
next message in the mailbox, with no issues at all. This would be a bug in  
the POP-3 client, if a single unaccessible message completely crashes it.  
The POP-3 client knows how many messages there are in a mailbox, and if it  
gets an error getting one of them, this does not block the client from  
skipping it and proceeding to the next message.

This is a bug with the POP-3 client, that should be forwarded to the POP-3  
client's support. There's nothing that the server can do, if the POP-3  
client is not handling errors correctly.

> Another bad thing that occured while corier-imap upgrade 4.18.2 -> 5.0.2: All  
> (!) our pop3 clients retrieved the copies of messages that were at the server

I'll look into it, but POP-3 isn't really meant to be a poor man's IMAP.  
Leaving messages on a POP-3 server is abuse of the protocol.