[ NNSquad ] Re: Comcast limits on outbound e-mail traffic?

[Richard Clayton <richard@highwayman.com>]

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In message <200711121813.lACIDxtA003351@chrome.vortex.com>, Lauren
Weinstein <lauren@vortex.com> writes

>Over on the NNSquad Forum, a poster is claiming that Comcast enforces a
>"secret" limit of 50 outbound e-mails per some (undisclosed) period of time
>for residential (presumably dynamic IP address) subscribers
>( http://forums.pfir.org/main/messages/714/777.html ).
>
>Can anyone verify or provide more information on this matter 

It continues to surprise me how little users seem to know about the ISP
business operates :(  This is commonplace.

In fact Comcast have a non-secret limit of 1000 recipients:

    http://www.comcast.com/customers/faq/FaqDetails.ashx?Id=4394

and Dr Occam would suggest that mechanism was considered first.

>or
>similar limits, if actually present, at other ISPs?

Service protection measures are very common (if an ISP's outbound email
service sends a lot of spam it gets blacklisted, which causes havoc for
all of the other customers). MTAs these days tend to have out-of-the-box
provisions for such schemes...

... here's a description of Exim's facilities

<URL:http://www.exim.org/exim-html-current/doc/html/spec_html/ch40.html#
SECTratelimiting>

... and here's where they came from

    http://www.ukuug.org/events/spring2006/programme/TFinch.html

They're usually set high enough that no-one notices (because otherwise
it costs the ISP a fortune in hand-holding legitimate customers).

Personally I'd argue that hard limits on emails or destinations are just
being lazy, you can get better results by counting delivery _failures_
since properly run mailing lists and mailshots don't get many failures,
whereas spam runs do.

- -- 
Richard Clayton                          <richard.clayton @ cl.cam.ac.uk>
                    Computer Laboratory, University of Cambridge, CB3 0FD

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