Shared mailboxes, users with dots and a bug in subscriptions

[Aki Tuomi]

> On 28/01/2021 16:55 Tobias Stein <tobias_stein at rockstable.it> wrote:
> 
>  
> Hi Aki,
> 
> Thanks for your prompt reply! :-)
> And because i classically forgot to attach
> the dovecot-sysreport, i'll deliver it now. :-)
> 
> 
> Yes, you're right. Setting :LAYOUT=fs would be a workaround.
> I'd also have to migrate every
> single mailbox to the new hierarchical layout.
> The hierarchical separator list->sep would
> indeed change to „/‟ and the subscriptions
> would be split differently.
> 
> Please correct me when i'm wrong, but
> the namespace/separator would have to be changed too,
> to prevent splitting on another "wrong" position.
> The current
> shared/root at example	com/test	subtest
> would become to
> shared	root at example.com	test	subtest.
> Which is also wrong because there is no user shared.
> So the namespace separator could be set to again something
> different (from „auth_username_chars‟ + "/+")
> like „^°!§%&=?;:#¹²³‟ which all would be ugly.
> And with namespace/sep set to „°‟ leading to the form
> shared°root at example.com°test	subtest.
> 
> But this would not resolve the actual bug, that subscriptions
> are not split and persisted correctly.
> In the end i would just be forced to use :LAYOUT=fs
> to mitigate the bug, even if i like the flat layout. :-)
> 
> I think there should be a default, which is valid
> for a common deployment with all features working.
> Maildir++ for sure is a great choice for this,
> but the implementation has a flaw:
> a hard-coded „separator‟, which collides with
> the DNS label delimiter, when storing subscriptions.
> 
> 
> Best Regards
> Tobias

You can also just change the namespace hierarchy separator to fix this:

namespace {
   separator = /
}

This will cause clients to redownload mails but requires no other changes.

Aki