[Dovecot] LSUB "" "" vs LIST "" "" (hacked Apple Mail problem)

[Robert Schetterer]

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Eyvind Bernhardsen schrieb:
> The LSUB command does not act like LIST when provided with an empty mask
> argument.  LIST responds with the hierarchy delimiter:
> 
>     * LIST (\Noselect) "." ""
>     OK List completed.
> 
> whereas LSUB doesn't return anything useful:
> 
>     OK Lsub completed.
> 
> RFC 3501 doesn't specify what LSUB should do in this case, but Courier
> IMAP has LSUB act like LIST.  The attached patch modifies
> imap/cmd-list.c to make Dovecot do the same.
> 
> 
> Why do I care about LSUB?  I'm using a hack for Apple Mail that replaces
> its LIST command with LSUB (something like what's described here:
> http://www.macosxhints.com/article.php?story=20040407062603804), to
> prevent it from syncing public folders from the Exchange server at the
> office.
> 
> The hack replaces _all_ LISTs with LSUBs, including the LIST "" ""
> Mail.app sends to discover the hierarchy delimiter.  Since dovecot
> doesn't give it any information in response to LSUB "" "", Mail.app
> defaults to using "/" as a delimiter, which means that trying to access
> a subfolder only results in an "Invalid mailbox name" error.
> 
> While this isn't really a bug in Dovecot, it's not inconceivable that
> other people than me could be affected by this problem (macosxhints.com
> has a substantial readership).  It's also tricky to diagnose, especially
> since the "Invalid mailbox name" message doesn't include the invalid
> mailbox name, so any bug reports you get are likely to eventually be
> filed under "crazy [Mac] users".
> 
> In fact, while Googling to figure out why Dovecot wasn't working for me,
> I came across at least one poster to this mailing list who had
> discovered that Mail.app was using "/" as a delimiter.  I can't be sure,
> but I'm guessing that his problem was related to mine.
> 
> Since the patch is tiny and doesn't hurt performance or make Dovecot do
> anything that contradicts the IMAP RFC, I hope you'll consider adding it
> to the official distribution.
> 
> 
> 
> Eyvind Bernhardsen
> 
Hi,
as i have one customer on courier only with apple mail
i got known of so many bugs with imap that i must say this is a broken
client in my eyes

- --
Mit freundlichen Gruessen
Best Regards

Robert Schetterer

https://www.schetterer.org
Munich/Bavaria/Germany
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