We have an old email server running Postfix/IMAP4, and new email server running Zimbra Network Edition under Ubuntu AMD64 OS.

I was trying to run imapsync to sync my old email box to new zimbra mail box. The command I type was:
./imapsync --nosyncacls --subscribe --syncinternaldates --host1 oldmailserver --user1 myaccountname --password1 mypasswd --host2 zimbramailserver --user2 myzimbraaccount --password2 myzimbrapasswd --noauthmd5

I have enabled clear text logins, but still received an error from my zimbra server, which is:
error login : [host2] with user [user2] auth [LOGIN]: 3 NO cleartext logins disabled

3 NO cleartext logins disabled
...propagated at /usr/bin/imapsync line 676.

tried the same flags but adding -ssl2 and then still get
Error connecting to host2:993:

Is there anything else I should enable or check?