Microsoft Confirms: Severely Throttling New IPs
Microsoft last week verified it is significantly throttling the volume of e-mail it will allow to come into its Hotmail accounts from new IP addresses.
The admission won’t come as a surprise to many e-mail service providers. However, it will help them explain to ornery new clients why their e-mail delivery rates temporarily drop when they switch providers.
“If we’ve never seen mail from you before, we’re going to limit the amount mail sent to us,” said Craig Spiezle, director of online safety at Microsoft Corp. “The message to the marketer is: ‘You want to be cautious. Don’t do your major holiday campaign, and on day one, drop a few million mails from a new IP address.’”
As Microsoft has increasingly begun to use the reputation of sending IP addresses to determine whether or not to accept e-mail from them, spammers have responded by distributing their blasts across significantly increasing numbers of IPs.
As a result, the vast majority of the time Microsoft encounters a new, low-volume IP address, it is that of a spammer, said John Scarrow, general manager, anti-spam technologies, Microsoft.
“Reputation is expanding botnets because they need many more IPs,” he said at the Authentication and Online Trust Summit in Boston last week.
But while the need for Microsoft to be wary of new IP addresses is understandable, the practice of throttling has been severely straining some e-mail service provider relations with their clients, particularly new ones, according to multiple sources who asked to remain anonymous.
Typically, when an e-mail service provider gets a new client, the first few campaigns show a significant drop in delivery rates, said an executive from one provider who asked not to be named. And just as typically, the client blames the drop on the new service provider, who must then begin a “forensics” process to find out why the dip in performance took place, the executive said.
Sometimes, much of the problem is the result of misreporting by the previous e-mail service provider. But often, it is the result of something happening on the receiving end. And since inbox providers are hesitant to be too free with information because spammers will use it against them, it is often difficult for e-mail service providers to give their new clients hard answers as to why their performance dipped.
Many suspect Yahoo! is also throttling e-mail from new IP addresses, as well, but won’t own up to it.
“We at least appreciate the fact that Microsoft has come clean about this,” said one e-mail deliverability specialist who wished not to be identified. “We just wish Yahoo! would do the same.”
Yahoo! spokeswoman Karen Mahon said yesterday afternoon she’d try and find out if her company is also limiting e-mail from new IPs, but hasn’t responded yet.
When asked how strictly Microsoft throttles e-mail coming from new sources, Spiezle said: “It’s going to be severely throttled.” He declined to get more specific.
He added, however, that a new IP can gain a reputation with Microsoft that will allow the sender to deliver e-mail at full throttle within 72 hours to a week.
“What we want to see is if we let in x amount of thousands of mail, do we get any complaints?” he said. “And then if we double it, do we get any complaints.”
He also refused to get specific about how many e-mails a day a mailer should send from a new IP in order to build its reputation, but indicated 50,000 to 100,000 might do it.
Microsoft also claims it receives 3.8 billion spam e-mails every day.
