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Fix an SBC Yahoo outgoing email issue with .Mac
Authored by: kchrist on Mar 01, '05 10:02:43AM

On the contrary, port 25 filtering is a very effective spam prevention measure and I applaud any ISP who does this. It's most important for dialup connections, but mail servers shouldn't be run on dynamically assigned IP addresses whether they're dialup, DSL, cable modem, or whatever.

About four years ago Earthlink rolled out port 25 filtering for all our dialup accounts. I was working in their network abuse department at the time, and my group was the driving force behind getting this change implemented. We were one of the first ISPs to do this nationwide and it had a HUGE effect on the number of spammers abusing our service. We saw numerous professional spammers -- people who would sign up 20 - 30 accounts per day with stolen credit cards and spam until we found and killed the account an hour or two later -- just disappear. See, with the port 25 filtering, they could no longer use open relays overseas or on cable modems, etc, from our service. The only way to send mail from one of our dialups was to do it through our mail servers where we would notice spam immediately. So they left and went to ISPs it was easier to spam from.

The other obvious benefit is that clueless users who set up insecure mail servers on their cable modems or whatever cannot be abused by spammers.

I'm sympathetic to the argument that stuff like this breaks the end-to-end nature of the internet, but we have to change with the times, and if people (ie, spammers; I use the term "people" loosely) are going to be assholes we have to take steps to stop them. The alternative will cause the internet to decrease in usefulness for everyone as opposed to the relatively few people with the legitimate need to send mail thorugh other SMTP servers.

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Fix an SBC Yahoo outgoing email issue with .Mac
Authored by: unclecal on Mar 02, '05 04:44:39AM

Blocking outgoing email on port 25 does nothing for the Macintosh user.
It does little for the PC user for that matter.
It's true it might protect the ISP from getting emails from infected Windows machines, but that won't last long.

Most experts agree, it's a weak stop gap measure at best. It hasn't even been adopted by Comcast or AOL which make up more then 50% of the broadband market share. So, it will do little to stem the Windows-propagated spam tide.

For the mac user it's just an annoyance.
No reason we should be inconvenienced by Microsoft's security flaws.

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Fix an SBC Yahoo outgoing email issue with .Mac
Authored by: kchrist on Mar 02, '05 02:42:01PM

Port 25 filtering is not meant to benefit end users directly, it's meant to inconvenience spammers and keep them from abusing the networks of the ISPs implementing the filter. The indirect benefit that end users get, regardless of OS they're using, is that is makes things harder for spammers, and therefore causes less spam to be sent out. I can assure you, widespread port 25 filtering put a serious crimp in spammers' activities.

AOL *is* filtering port 25 traffic, at least on some of their dialups. They were at the time anyway, and while they may have stopped, I find it unlikely. One of the reasons for this is that some of the backbone providers, UUNET for example, began requiring it of the ISPs that used their network. UUNET's requirement affected Earthlink, MSN, AOL, and probably dozens or more smaller ISPs that leased their POPs.

Please don't try to turn this into a Mac v. Window thing. This has nothing to do with Mac users, or Windows users, or the security flaws of any OS. While it does also help with spam sent from compromised Windows machines, the intended consequence was that it would stop spammers using throwaway dialup accounts and spamming through open relays. It accomplished this in a big way. Sure, it still happens, but not nearly as much as it did.

Unfortunately the spam war is an arms race. Spammers have since come up with other methods of getting their junk out. First they used insecure proxy servers, and then they started installing their own proxies delivered via e-mail viruses. Steps have been taken to deal with this, but their evolution does not invalidate the steps we've taken previously.

I agree that we need to find a balance between causing problems for spammers and as little inconvenience as possible for end users, but port 25 filtering affects an extremely small percentage of the internet-using population. Of that percentage, another very small percentage have a problem with simply using their ISPs SMTP servers. This is why use of the SMTP submission port (587/tcp) has become common over the past few years.

The point is, there's no reason to be upset about it. There are at least two trivial solutions to anyone affected by this problem.

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