It looks like the problem was with the milterd service.**
[root@webmail log]# grep 538E02D7A6C4 zimbra.log
Jun* 2 11:28:44 webmail postfix/smtpd[23728]: 538E02D7A6C4: client=rrcs-24-199-241-82.midsouth.biz.rr.com[24.199.241.82], sasl_method=PLAIN, sasl_username=sadams
Jun* 2 11:28:44 webmail postfix/cleanup[29320]: 538E02D7A6C4: message-id=<D54C655F-416E-4707-912A-E4A88278FD41@bigrocksports.com>
Jun* 2 11:31:49 webmail postfix/cleanup[29320]: 538E02D7A6C4: milter-reject: END-OF-MESSAGE from rrcs-24-199-241-82.midsouth.biz.rr.com[24.199.241.82]: 4.7.1 Service unavailable - try again later; from=<sadams@bigrocksports.com> to=<shannon_adams68@yahoo.com> proto=ESMTP helo=<[10.10.1.191]>
This details some of it:
Adjusting SMTP/milter timeout?
We had turned on the milterd service last month when we upgraded to 7. *For now, we just turned off the service and my test went out successfully.* We could probably tweak the time out settings for SMTP, but we will deal with that later.*
All my tests from Mac Mail work now that we turned off the milterd service.