Israeli ISP blocking outgoing SMTP

[Imri Zvik]

Blacklisting is very effective, but should be done carefully.
Senderbase-like solutions proved to be _very_ effective, without much of
false positives.
What I do object, is uceprotect-like blacklists who automatically block
huge ranges for a ridiculous amount of spam.

I do agree that blocking port 25, as tempting as it might sound for your
average abuse desk personnel, is a stupid idea.


-----Original Message-----
From: Oleg Goldshmidt [mailto:pub at goldshmidt.org] 
Sent: Tuesday, April 07, 2009 9:02 PM
To: Aviram Jenik
Cc: Imri Zvik; linux-il at cs.huji.ac.il
Subject: Re: Israeli ISP blocking outgoing SMTP

Aviram Jenik <aviram at jenik.com> writes:

> Noam didn't say blocking port 25 for everyone is a good thing or
> that he likes it - just that this is what ISPs in Europe and the US
> are doing that to fight spam.

Not in my experience. That is, unless I grossly misunderstand the
problem. In my mind, this means that the problem occurs when you
configure a foreign server as your SMART_HOST while connected to the
"octal 11" Israeli ISP.

If this is _not_ the problem, please accept my apologies and ignore
the rest.

I have just returned from a trip to Europe. I sent emails, using my
laptop, from two different Western European countries, from a hotel,
from coffee shops, from occasional unidentified public Wi-Fi spot,
etc. Presumably several different ISPs were involved, though I never
bothered to make a list.

Now, my laptop runs sendmail and has SMART_HOST configured to be my
Israeli ISP's mail server. Thus, when I send an email from abroad, I
am in a situation analogous to someone in Israel using a US server for
outgoing SMTP traffic. Not a single email during my week-long trip
(and I had to send quite a few) bounced or was lost. To me, this means
that Western European ISPs do *not* prevent SMTP traffic reaching
servers other than theirs.

Last time I was in the US was last August, I had no problem there,
either.

In general, this does not make much sense. Imagine a typical
Windows/Outlook user who has his "outgoing mail server" (SMART_HOST
equivalent) configured to something (by his company's IT people, he
himself does not know what an "outgoing mail server" is,
etc.). Imagine this person on a trip somewhere - he does not change
his configuration, but he doesn't normally have any problems sending
email.

If the "octal 11" Israeli ISP does it it is *not* following any common
practice. Oh, and I agree it is stupid, as is blacklisting.

-- 
Oleg Goldshmidt | pub at goldshmidt.org