ingress SMTP

Matthew Moyle-Croft mmc at
Sat Sep 13 17:39:04 CDT 2008

Frank Bulk wrote:
> How do you alert mail server operators who are smarthosting their e-mail
> through you that their outbound messages contain spam?
Typically a ticket gets injected into helpdesk who then contact them via 
email or via a phone call depending on the situation.  I don't think 
we've automated it as often these kinds of people don't react well or 
ignore it - so a human being needs to intervene and often give help.

We also take measures such as rate limiting the amount of email they can 
send (kbps, msg per hour wise) to limit the damage.

We offer a URL for customers that allows them to see their "spam" rating 
for their IPs (this includes if they're sending out viruses as well) - 
including a text only version (2 lines of text) so it can be easily 
parsed by machine if someone wanted to integrate it into their own checking.

We try and have default settings that protect us and the users as much 
as possible, but allow people who (at least think they) know what 
they're doing to change them to be more open.   Our general customer 
base tends to be biased towards the techy type who want this kind of 
thing.  (We sponsor things like the Australian Systems Administrator's 
Guild etc)

> Frank
> -----Original Message-----
> From: Matthew Moyle-Croft [mailto:mmc at] 
> Sent: Saturday, September 13, 2008 12:41 AM
> To: Bill Stewart
> Cc: nanog at
> Subject: Re: ingress SMTP
> Hi Bill,
> Bill Stewart wrote:
>> In some sense, anything positive you an accomplish by blocking Port 25
>> you can also accomplish by leaving the port open and advertising the IP
>> address
>> on one of the dynamic / home broadband / etc. block lists,
>> which leaves recipients free to whitelist or blacklist your users.
> Except that this tends to lead to a worse situation for people like
> yourself who wish to run a mailserver - because ultimately you'll have
> to resort to using an ISP's forwarder anyway because there will be more
> spam from the IP ranges you're in leaving to the wide world, thus a
> worse reputation, and so more blocking.
> ie.  by blocking outbound SMTP by default and getting customers to use
> our mail cluster their email is more likely to arrive and not be dropped
> as coming from a potential spam source.
>> I've toned down my vehemence about the blocking issue a bit -
>> there's enough zombieware out there that I don't object strongly to an ISP
>> that has it blocked by default  but makes it easy for humans to enable.
> That's what we do - by default most customers have a small ACL applied
> which protects them from traffic from various windows ports, ensures
> SMTP goes via our mail cluster etc.   Having customers send mail out via
> us is actually better because we do spam checking and can alert
> customers to their machines being compromised etc (or at least customers
> can look at their status themselves).   But, customers can easily turn
> the filtering off via the portal we have.
> We have no issues with customers running servers - most people don't,
> and those who do value the ability to do so.
> --
> Matthew Moyle-Croft - Internode/Agile - Networks

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