Dear Jholder,
I have post any other link before reading this read timeout issues. I have been search througth the wiki and other means to fine a solution on this but could not fine any answer and solution. try to disable the DNS lookup etc..
no luck at all. Can you help?
Here is the case, the I have a friend using a exchange for his company email domain. Only one domain on the server.
And we are using zimbra, 4.5.7 now.
And zimbra log show read timeout, and could not delivery the email just for this ip machine for some reason. And I believe it is something to do with the postfix configuration as he had another party using the postfix have the same problem.

Therefore, I set up any other machine just to locate the problem but that machine using zimbra 4.5.6 FC5 did go throught.
I have compared the setting on two machines, only different is that
one is the FC6 64 bit ( problem one)
one is the FC5 32 bit ( no problem one)

all the postfix setting are the same, I have compared them side by side.

here are the log, any solution?

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Sep 25 09:02:04 XXXXXX.COM amavis[6163]: (06163-11) Checking: VTR9lbE-lSqy [] <> -> <>
Sep 25 09:02:07 XXXXXXXamavis[6163]: (06163-11) FWD via SMTP: <> -> <>,BODY=7BIT 250 2.6.0 Ok, id=06163-11, from MTA([]:10025): 250 Ok: queued as 04A1539C8C5D
Sep 25 09:02:07 XXXXXXamavis[6163]: (06163-11) Passed CLEAN, LOCAL [] [] <> -> <>, Message-ID: <2002323042.151190682124090.JavaMail.root@XXXXXX .c om>, mail_id: VTR9lbE-lSqy, Hits: -2.179, size: 975, queued_as: 04A1539C8C5D, 2873 ms
Sep 25 09:02:07 XXXXXX postfix/smtp[18244]: 2457739C8C56: to=<>, relay=[], delay=3, status=sent (250 Ok: queued as 04A1539C8C5D)
Sep 25 09:07:07 XXXXXXX postfix/smtp[18251]: connect to[]: read timeout (port 25)
Sep 25 09:07:07 XXXXXX postfix/smtp[18251]: 04A1539C8C5D: to=<>, relay=none, delay=300, status=deferred (connect to[]: read timeout)
Sep 25 09:15:18 XXXXX postfix/smtp[27419]: connect to[]: read timeout (port 25)
Sep 25 09:15:18 XXXXXX postfix/smtp[27419]: 04A1539C8C5D: to=<>, relay=none, delay=791, status=deferred (connect to[]: read timeout)
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