[Dovecot] Is this really a user agent issue?

Willie Gillespie wgillespie+dovecot at es2eng.com
Fri Dec 24 00:08:18 EET 2010

Phil Howard wrote:
> I think this issue has been entirely misunderstood.  Have I explained it wrong?

I think there's been a bit of confusion here.  Everyone is saying 
similar things in slightly different ways.

The IMAP protocol has no way to "push" to the MUA that a folder 
(mailbox) has been freshly created.  This information must be "pulled" 
by the client, ie: LISTing all folders.

So, say we have an MUA connected and -something- (whether it be deliver 
or another MUA connected elsewhere) creates a new folder.  With IMAP the 
original MUA has no way of knowing that this just happened.  When it 
tries to create the same folder, the CREATE fails, because the folder 
already exists.

How the MUA handles this situation is up to the MUA.

I see a few possibilities:
1) it could ignore the situation and just show an error message to the user*
2) it could do a LIST and get an updated list of folders**
3) it could add the folder to its display***

* Sounds like what your MUA is doing.
** This could be fine and dandy, but many MUAs use the subscription list 
(LSUB) instead of showing all the folders (LIST).  So just because the 
MUA now knows the folder exists doesn't mean it will show it to you 
unless you SUBSCRIBE to it.
*** Whether this means that the MUA auto-SUBSCRIBEs you to the mailbox 
or not depends on what mode the MUA is running in.  It seems like this 
is what you want your MUA to do instead of #1.

If I were a programmer, #1 would definitely be the easiest to do.  Then 
I wouldn't have to care WHY the CREATE failed, I just show an error 
message no matter what.

So in answer to the question in the subject, "Is this really a user 
agent issue?" Yes.  The server is doing nothing wrong according to protocol.

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