Mark Constable wrote:
On Thursday 30 March 2006 18:25, Gordon Messmer wrote:
I've been wondering how that's going to play out, myself. The first
thing I'd expect ISPs to do is establish an egress filter to disallow
connections to SMTP servers other than their own, entirely. Remote SMTP
servers would probably only be usable if they're available on port 465
(SSL) or 587 (MSA), or via VPN.
What if all clients can only use SMTP ports after authenticating,
and perhaps only then via SSL (465), would such egress filtering
still be required ?
I mean to imply that ISPs probably will (and maybe even ought to)
prevent their users from connecting to SMTP servers other than their
own. A lot of zombie-ware will send spam from desktop PCs, which
doesn't work if those PCs can't connect to the destination SMTP server.
To maintain some sort of balance, MSA and SMTPS can be left enabled,
since there's little risk of malware connecting to those services.
So, regardless of how the ISP's mail server is configured, and what it
requires, they will still probably want to put up an egress filter to
prevent their customers from reaching out on port 25.
There are a couple of ways to limit mail through your own system.
And aside from your suggestion below ?
Get creative. Most firewalls allow connection rate limiting, though a
rate limit in a firewall isn't going to be as "nice" to users as giving
them a message (in the SMTP dialog) explaining what's going on.
There's a "ratelimit" filter in my pythonfilter package that limits the
number of messages per IP, for instance. :)
A single user is probably locked to a single IP so that would be
good enough to work with. URL please ? Any docs ?
http://phantom.dragonsdawn.net/~gordon/courier-patches/courier-pythonfilter/
There's *some* documentation, but I'm not sure if it addresses your
concerns specifically. Have a look.
So I take there is no native built-in support for courier-mta to
handle outgoing rate limits ?
Not really.
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