OK - Yes it does support Idling

great thanks phoenix
[root@zim.shek.com ~]# openssl s_client -crlf -quiet -connect 192.168.1.139:993
depth=0 /C=US/ST=N/A/O=Zimbra Collaboration Suite/OU=Zimbra Collaboration Suite/CN=zim.shek.com
verify error:num=20:unable to get local issuer certificate
verify return:1
depth=0 /C=US/ST=N/A/O=Zimbra Collaboration Suite/OU=Zimbra Collaboration Suite/CN=zim.shek.com
verify error:num=27:certificate not trusted
verify return:1
depth=0 /C=US/ST=N/A/O=Zimbra Collaboration Suite/OU=Zimbra Collaboration Suite/CN=zim.shek.com
verify error:num=21:unable to verify the first certificate
verify return:1
* OK zim.shek.com Zimbra IMAP4rev1 server ready
. capability
* CAPABILITY IMAP4rev1 AUTH=PLAIN AUTH=X-ZIMBRA ACL BINARY CATENATE CHILDREN CONDSTORE ENABLE ESEARCH ESORT I18NLEVEL=1 ID IDLE LIST-EXTENDED LIST-STATUS LITERAL+ LOGIN-REFERRALS MULTIAPPEND NAMESPACE QRESYNC QUOTA RIGHTS=ektx SASL-IR SEARCHRES SORT THREAD=ORDEREDSUBJECT UIDPLUS UNSELECT WITHIN XLIST
. OK CAPABILITY completed
[B]* 2 EXISTS
* 0 RECENT
* OK [UIDVALIDITY 1] UIDs are valid for this mailbox
* OK [UIDNEXT 573] next expected UID is 573
* FLAGS (\Answered \Deleted \Draft \Flagged \Seen $Forwarded $MDNSent Forwarded $Junk $NotJunk Junk JunkRecorded NonJunk NotJunk)
* OK [PERMANENTFLAGS ()] junk-related flags are not permanent
* OK [HIGHESTMODSEQ 354] modseq tracked on this mailbox
. OK [READ-ONLY] EXAMINE completed
. idle
+ idling