On 2013-08-19 23:00, Stan Hoeppner wrote:
- a IMAP client opens one connection *per folder*
What do you mean by "per folder"? I've been limiting Tbird to 2 IMAP connections for many years and, unsurprisingly, it never opens more than two IMAP connections to Dovecot no matter how many folders I access, tabs I have open, or searches I perform, etc:
tcp 0 0 192.168.100.9:143 192.168.100.53:1663 ESTABLISHED 13189/imap tcp 0 0 192.168.100.9:143 192.168.100.53:1672 ESTABLISHED 13192/imap
And with the default TB limit of 5 it never opens more than 5. Which clients exhibit this "per folder" connection behavior? That seems totally unnecessary.
Any client which supports the 'IDLE' command does this; it's a mechanism to avoid that a client has to poll the IMAP server for new mail. The client does an 'IDLE' call *per folder* which only returns when the server adds new mail to the folder. Hence, the IDLE call blocks the connection, which is why mail clients which use IDLE have to establish multiple IMAP connections, one per folder which is monitored using this feature.
-- Frerich Raabe - raabe@froglogic.com www.froglogic.com - Multi-Platform GUI Testing