SpamCop blocks Yahoo (again) – Who is to blame?

SpamCop blocks Yahoo (again) – Who is to blame?

While checking our server logs, we noticed a lot of genuine yahoo email addresses being blocked from sending emails to our customers. This is because the IP that the email is coming from is listed within the SpamCop blacklist.

A blacklist is a list of IP addresses that have been found to be sending spam, malware and phishing emails.

How are they detected?

There are many trapboxes and honeypot traps which are not real email inboxes. Their sole purpose is to receive emails and analyze their contents. When any suspect items are found and confirmed, the IP address that the emails came from are sent to a blocklist.

You can view a Yahoo IP being blocked on SpamCop. A quick lookup confirms that this IP is owned by Yahoo.

The IP address is not the IP of the end user, but the IP of the system sending the email. In this case, the IP that was reported to SpamCop belonged to Yahoo.

How the email gets bounced

When any system tries to send an email, their system connects to the system that they are sending the email to and after a handshake, the receiving system checks that everything is okay before it accepts the email.

Part of this process within our system is checking the IP of the sending system against a number of blocklists to ensure that it has not been reported for anything naughty. If it has been reported and is listed within a blocklist, the email is then refused.

Who is to blame?

There is a lot of chatter about this online and many people are blaming SpamCop as well as other blocking systems. However, the system that sends email is responsible for all emails that they send and they need to ensure that they are not allowing spam, malware of phishing emails to be sent.

Therefore, we find it hard to blame anyone else except Yahoo as it is their system that is allowing these emails to be sent. In recent weeks, we have had a number of customers contact us who are receiving spam, malware and phishing emails from yahoo. These emails are NOT going through our system and therefore are not being filtered, they are going straight from yahoo to our customers yahoo or gmail email addresses.

It seems to us that Yahoo is doing very little, if anything at all to prevent these types of emails being sent from their system. This is why we prefer to use gmail, as it has over the years, proven to be more reliable than other email systems we have used.

What can be done?

The only people who can prevent the IPs from being blocked are Yahoo. However, we are looking at dropping some blocklists and instead, we will scan every single email to make sure that it contains no malicious link, phishing attempts or malware. While this will allow emails to be received from yahoo IPs that are blocked, it will not prevent all spam. We will use a secondary system to scan for spam, which should be able to detect most, if not all of the spam emails.

If you are experiencing issues receiving emails from yahoo users, you can request that they email your yahoo or gmail (or other) email address, bypassing your domain email address. For example, instead of emailing someone@your, they would email

  • David Watkinson
    Posted at 18:02h, 25 August Reply

    Update: We have dropped some blacklists and started scanning every single email to ensure it is authentic and not spam. This consumes a lot more processing power, but ensures that our customers experience fewer issues.

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