Why Is It So Hard To Keep IPs Off Spam Blocklists?

The only people who like spam are spammers, and they like it because it makes them money. At publication, the average amount of legitimate email sent daily is 64.91 billion while average daily spam volume dominates at 374.90 billion. If there was no way to stop spam reaching users, email would be essentially useless. The noise would far outweigh the signal.

To stop spam being delivered, there are many layers of filtering between sender and receiver; from filtering by email providers and third-party filtering such as MailChannels; to the spam recognition and filtering mechanisms included in modern email clients.

DNS Blocklists

DNS blocklists—also known as blackhole lists—are part of the internet’s immune system. They help email inbox providers, ISPs, and other organizations stop spam before it reaches their users.

DNS blocklists can be created by anyone. Many network administrators and inbox providers maintain private lists of IP addresses their email systems won’t deliver. Third-party blocklists are created and managed by specialist organizations, including SpamHaus and SpamCop. ISPs and other organizations that deal with a lot of incoming email don’t want to have to maintain huge and up-to-date blocklists internally, so they outsource the problem by subscribing to third-party blocklists.

Avoiding Blocklists

The best way to ensure your IP doesn’t appear on a blocklist is to ensure your organization’s outgoing email is spam-free. However, because spam is such a huge problem, blocklist maintainers can have a trigger finger when it comes to including IP addresses on their lists. That presents a problem for email providers and other organizations who rely on having their email delivered.

The organizations that maintain blocklists “work for” the ISPs and inbox providers and really don’t like it when spam gets through to their users. They don’t work for the organizations who send email. That means the incentives of blocklist providers lean towards a “block and ask questions later” approach. If they think that quantities of spam above a certain threshold originate from an IP or block of IPs, they will add those IPs to a blocklist—they don’t care whose fault it is.

Once an IP is on a blocklist, it is possible to have it removed, but it can be a lot of work. The blocklist maintainers would rather keep false positives in their list than let spam through, because their loyalty is to their subscribers, not email senders. That said, most reputable blocklist providers want to maintain accurate lists.

Being blocklisted is a risk for any organization that sends email, and the only real solution is to proactively monitor your organization’s outgoing email to ensure it doesn’t include spam. If spam isn’t released to email inbox providers, large organizations, and ISPs, the reporting mechanisms that lead to IPs being included on blocklists won’t be triggered.

MailChannels Outbound is designed to help your business stay off IP blocklists. Using digital signature technology, we scan your network’s outbound email to ensure no spam is present that could risk your IP reputation. If we find spam, we send an alert that allows you to locate and block the source. Read more about our technology here.