On 9/19/2011 5:36 AM, Tom Clark wrote:

Hi Paul,

It's coming from the same IP address through his ADSL. Hence he gets the problem with max_userip_connections.

I think I tracked down the problem. He's been using K9 mail which seems to have a problem where it doesn't release a connection and has 1 connection per subscribed folder....

Ta,

Tom

If you figure it out, please post the solution, because we're running into a similar issue right now with K9 mail where it's causing us to get this error:imap-login: Disconnected: Connection queue full

If it is the same problem with K9 (although Timo doesn't think it is) we fixed it on the K9 machine by turning off PUSH mail folders.

Tom

-----Original Message----- From: dovecot-bounces@dovecot.org [mailto:dovecot-bounces@dovecot.org] On Behalf Of Timo Sirainen Sent: 19 September 2011 7:12 PM To: Asai Cc: Dovecot Mailing List Subject: Re: [Dovecot] mail_max_userip_connections=10

On 19.9.2011, at 20.43, Asai wrote:

If you figure it out, please post the solution, because we're running into a similar issue right now with K9 mail where it's causing us to get this error:imap-login: Disconnected: Connection queue full

That's a different problem. You need to increase number of login processes / connections. http://wiki2.dovecot.org/LoginProcess

On 9/19/2011 7:36 AM, Tom Clark wrote:

Hi Paul,

It's coming from the same IP address through his ADSL. Hence he gets the problem with max_userip_connections.

I think I tracked down the problem. He's been using K9 mail which seems to have a problem where it doesn't release a connection and has 1 connection per subscribed folder....

The reasoning behind the multiple socket communication design in the IMAP protocol is flawed, thus we end up with problems like yours, and others. It may have looked good on the white board but it doesn't seem to add benefit in production--only add problems. At least from an SA's perspective. Just about every other modern internet protocol gets by with a single socket, and many of those applications are more complex than IMAP.

Multiple virtual channels are a good idea at the data link layer of WAN communications links, and work well there. They're a lousy idea at the application layer, however, as the IMAP protocol clearly demonstrates. Everything IMAP does over multiple sockets could have been accomplished over a single socket, with no noticeable decrease in performance, but with fewer SA headaches and fewer server resources consumed.

I eagerly await a successor to the current version of IMAP, which will hopefully do away with this problematic, unnecessary, multiple socket nonsense. It may be a long wait, unfortunately...

-- Stan

Thanks Timo. I've been doing some investigation. Apart from K9 being fundamentally broken 10 is fine!

I'll try the remote fix.

-----Original Message----- From: Timo Sirainen [mailto:tss@iki.fi] Sent: 22 September 2011 2:49 PM To: Tom Clark Cc: dovecot@dovecot.org Subject: Re: [Dovecot] mail_max_userip_connections=10

On 19.9.2011, at 11.27, Tom Clark wrote:

Is there anyway of whitelisting an IP so that it can ignore mail_max_userip_connections=10?

With v2.0 in theory:

remote 1.2.3.4 { mail_max_userip_connections = 0 }

I don't know if it actually works.

What should we set mail_max_userip_connections too realistically? 10 seems a bit low?

It's 10 because I thought it would be enough :)