On Thu, Nov 01, 2012 at 08:37:43AM +0800, Fred Ho wrote: > The problem happened intermittently with different senders and > I found it usually involved multiple recipients and have attachments.
> What I don't understand is Postfix qmgr took over 2 hours later > to process that stucked mail while the ISP has retried the mail > 2nd time in less than an hour and was delivered successfully. I > don't see any deferred mails though. This is not the case, the queue-manager processed the message as soon as it entered the queue. > I deliberately tune up the timeouts to see if it's the problem. Wrong timeouts (output not input) and unwise tuning. Revert to default settings. As I said before: > You can add one of the more frequent problem senders to "debug_peer_list" > and we'll see when the SMTP server receives ".<CRLF>". Otherwise you > need to capture a tcpdump "pcap" file of the problem transactions and > look at packet timestamps. -- Viktor.