dovecot - Jan 2021 - Shared mailboxes, users with dots and a bug in subscriptions

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 ?^?!?%&=?;:#???? 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
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> 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 ?^?!?%&=?;:#???? 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