Well according to those log entries it has successfully injected a email into Zimbra.
Code:
Sep 8 14:34:36 zimbrawebmail postfix/smtpd[2554]: disconnect from localhost.localdomain[127.0.0.1]
Sep 8 14:34:36 zimbrawebmail amavis[4806]: (04806-02) Passed CLEAN, LOCAL [127.0.0.1] [209.85.198.233] -> , Message-ID: <61eef310809080533p59c9d26ft7ba890fc6a77b993@mail.gmail.com>, mail_id: DcjSP+61V0hr, Hits: 0.102, size: 3348, queued_as: EB8B92F58282, 11946 ms
Sep 8 14:34:36 zimbrawebmail postfix/smtp[2549]: 06B4D2F58214: to=, relay=127.0.0.1[127.0.0.1]:10024, delay=16, delays=0.1/0.03/7/8.8, dsn=2.0.0, status=sent (250 2.0.0 Ok: queued as EB8B92F58282)
Sep 8 14:34:37 zimbrawebmail postfix/qmgr[5892]: 06B4D2F58214: removed
Sep 8 14:35:46 zimbrawebmail postfix/lmtp[2557]: EB8B92F58282: to=, relay=zimbrawebmail.server.net[192.168.5.150]:7025, delay=70, delays=0.01/0.06/2.7/67, dsn=2.1.5, status=sent (250 2.1.5 OK)
Sep 8 14:35:47 zimbrawebmail postfix/qmgr[5892]: EB8B92F58282: removed