Enhance IMAP server to allow general.cfg IMAP_CONNRATE_SLEEP=microseconds
This ER comes from investigation of SWA download error when system is fully loaded on RHEL7.
This may not fix anything but at least it allows the sleep time to be tuned down from previously fixed 1 second.
The sleep kicks in when the IMAP connection rate hits a limit, normally 10 connections per second set by installer.
By default (no general.cfg setting) the sleep time will remain 1 second.
To change it to 0.1s set IMAP_CONNRATE_SLEEP=100000 and restart all IMAP processes.