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On 2010-02-04 11:06, Paul Galati wrote:
"CommuniGate Pro Discussions" <CGatePro@mail.stalker.com> on February 3,
2010 at 8:44 AM -0500 wrote:
Note that in both cases the reported errors are related to connection
problems (the connection was explicitly reset by the remote peer, or it
was dead for 5 minutes). This may indicate a problem with the network or
an activity of some anti-virus or a like working on the SMTP level.
The problem was stemming from our Cisco ASA 5505 ESMTP inspection filter.
Evidently there is a known 998 byte default that has been causing
problems. Once I turned that inspection off, mail flowed like brand new
pipe, except for Yahoo which is not our fault.
In my opinion, those filters are in place to "protect" bad or badly
configured mail servers. CGP is usually neither of those, and the
firewall SMTP filters hurts CGP efficiency and proper function.
I have been informed that because I disabled the ESMTP inspection, outside
people, if they knew how, could access the server via telnet on port 25
and possibly send mail through that. Is this true and if so, what might I
do to prevent or decrease the chances of an uninvited guest relaying
through my server.
Opening a TCP connection on port 25 is THE method to send messages. Of
course you want that. Relaying through your server will not be possible
if your CGP is configured not to allow relaying of outside addresses
(default configuration).
NH
Thanks for your time.
Paul
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