Giuseppe De Nicolo':
> On 09/18/2014 05:40 PM, Wietse Venema wrote:
> > Giuseppe De Nicolo':
> >
> >> 136.231890 217.72.32.234 212.19.117.109 SMTP 227 C:
> >> MAIL FROM:<giampaolo.marcol...@bertoliniassociati.it> SIZE=2857 |
> >> RCPT TO:<giulio.digior...@oapointgroup.it>
> >> ORCPT=rfc822;giulio.digior...@oapointgroup.it | DATA
> >> 136.233724 212.19.117.109 217.72.32.234 SMTP 131 S:
> >> 250 2.1.0 Ok | 250 2.1.5 Ok | 354 End data with <CR><LF>.<CR><LF>
> >> 136.441076 212.19.117.109 217.72.32.234 SMTP 131 [TCP
> >> Retransmission] S: 250 2.1.0 Ok | 250 2.1.5 Ok | 354 End data with
> >> <CR><LF>.<CR><LF>
There is another possibility.
The SMTP client sends MAIL FROM/RCPT TO/DATA as one request
(SMTP command pipelining, RFC 2920), that's why Postfix replies
with 250/250/354 as one response.
It is possible that there is a device in the path that tries to
read SMTP conversation and that drops packets it does not understand.
Stuff like that tends to be built into a network firewall.
In that case, see what happens when you configure
# postconf -e 'smtpd_discard_ehlo_keywords=pipelining'
# postfix reload
If that solves the problem then you can make this selective per
client IP address with smtpd_discard_ehlo_keyword_address_maps.
Wietse
