After upgrading from Kolab 3.4 to Kolab 16 according to the upgrade notes, it was no longer possible to send any mail. I'm now running pykolab-0.8.3-3.1.el7.kolab_16.noarch.
The following was seen on Postfix logs:
Aug 8 19:21:07 posti postfix/submission/smtpd[13011]: C4B9D40934C6: client=localhost[::1], sasl_method=LOGIN, sasl_username=username@domain.tld Aug 8 19:21:07 posti postfix/submission/smtpd[13011]: C4B9D40934C6: reject: DATA from localhost[::1]: 554 5.7.1 <DATA>: Data command rejected: Sender access denied; from=<username@domain.tld> to=<externaluser@otherdomain.tld> proto=ESMTP helo=<server.domain.tld>
I was able to work around the issue by replacing the /usr/libexec/postfix/kolab_smtp_access_policy file from an earlier version, but I don't think this is a preferred solution :) (both versions attached, ...34 works, ...16 doesn't).
In addition, the following is logged in pykolab.log periodically, no idea if it has anything to do with this issue:
2016-08-09 14:04:14,678 pykolab.auth ERROR An error occured using _persistent_search: TIMEOUT() 2016-08-09 14:04:14,680 pykolab.auth ERROR Traceback (most recent call last): File "/usr/lib/python2.7/site-packages/pykolab/auth/ldap/__init__.py", line 3059, in _search secondary_domains File "<string>", line 10, in <module> File "/usr/lib/python2.7/site-packages/pykolab/auth/ldap/__init__.py", line 2738, in _persistent_search resp_ctrl_classes={ecnc.controlType:ecnc} File "/usr/lib64/python2.7/site-packages/ldap/ldapobject.py", line 476, in result4 ldap_result = self._ldap_call(self._l.result4,msgid,all,timeout,add_ctrls,add_intermediates,add_extop) File "/usr/lib64/python2.7/site-packages/ldap/ldapobject.py", line 99, in _ldap_call result = func(*args,**kwargs) TIMEOUT