Sendmail not accepting connections on port 25
freebsd at edvax.de
Fri Jul 22 08:32:20 UTC 2011
On Thu, 21 Jul 2011 22:34:26 -0400, Robert Huff wrote:
> ssgriffonuser writes:
> > > My isp is blocking outgoing traffic on port 25.
> > Yeah, it looks like your right. I never would've considered my ISP
> > blocking outbound traffic from my home, but I suppose it makes
> > sense.
Does _not_ make sense as it just hides symptoms, but does
not cure the initial problem.
> It is my understanding many I.S.P.s in the U,S, do, as part of
> spam control procedures. I am obliged to relay through my I.S.P.;
> after some initial set-up issues, this works flawlessly as long as
> at least one relay machine is up.
Same here - but different.
Due to the fact that more than 90% of world's mail
traffic is spam, many providers of mail services have
the policy to _not_ accept mail coming from a "suspicious"
IP. This is mostly ranges of dynamic IPs assigned to
"dial-up" (home consumer) services, but may also contain
other "blacklisted" IPs. In conclusion, you often have
the situation that you can actually _send_ a message,
but the target ISP's mail server will deny to accept it.
The same way of "manipulating the symptoms", I relay
my mail through my ISP's MX. Thanks to sendmail's
SmartHost setting, this is easy once set up. In the
mail logs, you can then see when messages are commited
to the MX (you do _not_ see delivery status to target
Blocking _outgoing_ "mail traffic" is also an interesting
approach, so my initial guess "check if ISP is blocking
something" was right... :-)
The initial problem, the "creation" of spam, is mainly
due to hijacked "Windows" PCs (and servers) in homes and
offices (the larger the "better"). Most people who run an
own mailserver, and even if it's just for outgoing mail,
do this in a _proper_ way. Sadly, those have to suffer
from the carelessness of the masses. Business as usual.
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...
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