• United States
larry chaffin
CEO and Chairman of Pluto Cloud Services

SpamCop disrupts millions of e-mail accounts by blocking Yahoo e-mail servers

Jun 01, 20114 mins
Cisco SystemsData CenterMalware

Businesses using Yahoo cloud e-mail are up in arms with little recourse to make SpamCop change its blacklist policy on Yahoo mail.

SpamCop has decided to block all e-mail coming from Yahoo servers, even if the e-mail is legit and part of Yahoo’s business cloud services. On Monday I was replying to a email from a customer and a vendor, when I received the message below.

Remote host said: 554 5.7.1 Service unavailable; Client host [] blocked using; Blocked – see [RCPT_TO]

At first I thought it was the customer and the vendor, but they told me that they do not use this service. I then called Yahoo who told me on the phone that SpamCop is blocking all Yahoo email server by IP address. There is nothing they can do and sometimes it will time out after a day. This was not good enough for me so I did some more digging and called some friends, it seems that many service providers or ISPs are using SpamCop. The end customer has no idea that they are using it and also no idea that email is getting blocked. I then decided to send a email to SpamCop and this was the email I received back today.

—–Original Message—–

From: SpamCop/Richard []

Sent: Tuesday, May 31, 2011 7:15 PM

To: larry chaffin

Subject: Re: BL dispute: IP:  This IP address is a webmail server that belongs to Yahoo and is being

used to send out large amounts of spam, including fake pharmacy spam,

fraudulent 419 scams and others.  The amount of spam being sent through

Yahoo has grown exponentially to the point it is tripping our listing


We can do nothing to stop the spam at its source, but we can help others

block spam, including those that have chosen to refuse any mail from

identified spam source IP addresses.  Only Yahoo can stop the spam

coming from their network.  You should contact Yahoo with your

complaints as only they can stop the spam.  Once the spam is stopped, or

at least slowed, the server IP will delist from the SpamCop Blocking List.


Please include previous correspondence with replies


A little more digging and I found this forum thread which began two weeks ago on the SpamCop support site, with a heading of “[Resolved] Yahoo Mail blocked?


May 10 2011, 01:58 AM =, and many other Yahoo servers, are sending HUGE quantities of spam to our users and to our system. It has been going on for a long time now. I don’t expect to see any change soon. The servers will remain on our blocking list until the spam stops.

– Don D’Minion – SpamCop Admin – – service[at] –

A reply from forum member “Derek T” further explained the situation:

“The good news is that Yahoo has (according to Senderbase) 5,507 email servers. Of these only a few will be on the block-list at any one time so it’s not a case of ‘hanging around for (at least) 24 hours every time someone uses Yahoo to send spam’ 99 times out of a hundred (or more) your mail will be sent through one of the servers that is not on then blocklist. You were just unlucky this time. The wisdom of using a free, spammy, mailserver for important business mail is a whole other question.”

But “Derek T” has it wrong. Yahoo also offers paid, cloud-based e-mail for businesses. I have called my customer and my vendors back today and they are not too happy that they have customer emails and corporate emails using a hosted Yahoo business service that are being blocked. My company is using another email account (on Gmail) to get emails to customers and vendors who are having this issue.

What gives SpamCop the right to block Yahoo IP addresses in this way? It is absurd. If the only way for a spam company to control spam is to block all the mail coming from an IP address, might I suggest that the company invest in some spam filter algorithms?

There was a call on Twitter about this problem asking all companies to boycott SpamCop for making this choice. It is a huge interruption to business owners who use Yahoo’s hosted service.  It is also unfair to those companies who don’t the Yahoo service or SpamCop directly but are affected because their ISP or business partners are using one of these services.

Perhaps the FCC should look into SpamCop for blocking IP addresses like this and causing such problems. I, for one, would like to see the SpamCop face fines or other measures to make this irresponsible behavior stop.