Israeli ISP blocking outgoing SMTP

[Aviram Jenik]

On Tuesday 07 April 2009 11:01:52 Oleg Goldshmidt wrote:
> 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.

[...]

> 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

You just got lucky.

Some ISPs will only block you after a number of outgoing port 25 connections 
to different IPs. Others block outgoing 25 completely. 

Try and remove the SMART_HOST to have sendmail send emails directly (as the 
Internet was built to allow) and revisit those ISPs. You'll probably be 
blocked. Leave SMART_HOST in and try a few more ISPs in Western Europe and 
the US and you will probably get blocked. 
See for example:
http://www.postcastserver.com/help/Port_25_Blocking.aspx


>
> 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.

No argument there. It is incredibly stupid, but unfortunately unpreventable 
due to the sheer number of moron blacklisting services.

- Aviram