Yahoo's Amazing Disappearing Mail Servers

Golygydd Max writes "A Techworld story reveals that the reason Yahoo email has delivery problems is that the company's mail servers mysteriously close once in a while." From the article: "According to trimMail's Email Battles site, which recently monitored 16 of the company's advertised email hosts 240 times over a half hour period, only 133 of its probes were answered. Many of the servers were closed and unavailable. Overall availability ranged from 25 percent to 75 percent over the admittedly short test period. The average availability was 55 percent, with the worst of the servers available only 7 percent of the time."

Comments

As long as one of them is up...

[jeffmeden]

All you need is one server to have a functioning email system. Can anyone say 'MX priority list'? Of course maybe when each user is taking in hundreds of pieces of spam a day things might get *a little slow*...

Re:As long as one of them is up...

[caluml]

Plus your average mail server will hold your mail, and keep trying for 5 days before giving up. So, as long as 1 of Yahoo's servers is up for a decent period in a 5 day period, mail shouldn't be lost. Course, users might be annoyed with the delays. :)

Shouldn't be responsible for delivery problems

[pen]

Servers being down some of the time shouldn't cause large-scale delivery problems. Remember, when e-mail protocols were being designed, a lot of these servers were down for a good portion of each day. E-mail protocols were designed to deliver e-mail in whatever window existed. If the receiving server is down, the sending server will try again for a good while before giving up.

Also, as someone else has already mentioned, there are the MX priority lists...

Re:Is this caveat emptor day?

[Alex P Keaton in da]

Actually, yahoo has a significant business email program...

http://smallbusiness.yahoo.com/business_services /
They also have a lot of people who use Yahoo as a web host (paid) and get email @theirdoman.com....
So Yahoo mail is not always free.....

Never had any problems

[MadMorf]

I've used Yahoo for %100 of my personal email for the last 6 years.

And, as an email admin, I also use it to test systems, both mine and others, and it always works...

If the servers are up and down all the time, I've never noticed it...

I'd file this under FUD...

Not Meaningless

[twitter]

Email is DESIGNED to handle failures of this kind.

Yes it is.

The web itself is supposed to be redundant, but it's not. Cox, under pressure from M$ and AOL, made sure you could only use their SMTP server on their network. That leaves every computer on their network reliant on their servers or web mail and it sucks. The only thing that's distributed now are the spam and DoS attacks. Yahoo's failure is just andother example of what a bad idea to concentrate services in one place. If everyone ran their own mail server, things would work much better. To DoS that, you would have to turn off everyone's computer.

Re:no wonder

[arivanov]

You are amazingly pretty much on target.

95%+ of the SPAM reduction on Yahoo is due to the use of greylisting. Essentially the mail server simulates that it is unavailable to anyone it does not know as a well behaved relay. A well designed MTA will come back and deliver the mail later and the server will accept it. A SPAM zombie will skip to the next target.

A probe will be judged a zombie until proven opposite. A probe that does not try to deliver mail or do anything usefull will cause the SPAM ranking of the originating IP to go up until firewall shielding rules are deployed. From there on you cannot even reach the servers in question until the entry expires. In addition to that well behaved MTAs go to MXes in a predictable order. Anything hitting MXes in a different order is immediately considered a SPAMBOT and will cause the greylisting code to either set a "refuse" with a high timeout on it or (if the code is there) to raise firewall shields outright to tarpit any connections from the BOT. This also essentially disallows you to test any specific host for MX connectivity without testing the entire MX pool in correct order. If you do, you guarantee yourself a blacklist entry which will be generated automatically on the fly.

By the look of it this pretty much summarises what has happened here. Quite funny actually. It is indicative of the current crop of "security companies" and professionals. They claim understanding of security without knowing how things are done.

Re:Dumb spam protection?

[rhizome]

It's also a common practice to use a delayed SMTP response to thwart spammers. Maybe this person's ping script doesn't account for any delay and thus returns an error.