[Dovecot] Maximum number of connections from user+IP exceeded

[Stan Hoeppner]

On 8/20/2013 1:47 AM, Ben wrote:
>> IDLE is not required for this.  Polling, which is the default on all
>> MUAs,
> 
> Not entirely sure I'd call it "the default", Thunderbird seems to setup
> for IDLE as default these days, and I suspect Apple Mail and any of the
> other popular ones do too.
> 
> The source code probably looks something like
> if (canIdle) then
>     {do stuff}
> else
>     {do polling}

I haven't looked at a recent fresh install config of TB.  If they have
started enabling IDLE by default it's recently, and they'd have been
required to increase the default 5 cached connections.  Otherwise many
folk would never see new mail notification on some of their server side
sorted folders.  And Joe and Susie Sixpack have no knowledge of the
relationship between connection (socket) count and IDLE requirements,
and I'd guess no MUA has documentation explaining this.  I'm pretty sure
Mozilla does not.  I'm sure there are forum posts about it, but I doubt
official documentation exists.

For IDLE to work seamlessly requires basically 3 things:

1.  MUA counts all IMAP folders and
2.  Always maintains $folder_count sockets
3.  IMAP servers must allow basically unlimited sockets

In a closed environment such as a corp/uni this can be achieved, and
without unlimited sockets, if staff can enforce a limit on folder count.
 In an open environment such as an ISP or freemail provider, they'd have
to allow unlimited sockets.  Some may do so currently.  I have no
knowledge of what such providers are doing in this regard as I don't use
them nor support anyone who does.

-- 
Stan