Whether you’re a small business or a large company, being able to email your customers when you need to is essential. However, this vital capability can be compromised due to many reasons, such as the actions of malicious hackers gaining unauthorised access to mailboxes or vulnerable websites in order to send spam. The more spam that gets sent, the more likely your email address, domain or even your ISP's mail server will be placed on some sort of blacklist.

Blacklist meaning

Blacklists are most commonly a collection of email or IP addresses which have been flagged for sending spam. Many email hosting providers will use these public blacklists as part of their overall efforts to limit the spam they receive to their network. This is done by blocking communications from IP addresses that are suspected of malicious activities. The blacklist itself is a list containing ranges of IP addresses that are blocked.

The purpose of this is to guard the web and other internet servers from attack. This is achieved by setting rules within the host’s server software or hardware routers about what is treated as an attack and then stopping the computers from connecting to that traffic again.

This isn’t just emails being redirected to an inbox’s spam folder, however. When an IP address is blacklisted, all emails sent will instead be bounced back until the IP address is removed from the blacklist.

Why does blacklisting happen?

Blacklistings are triggered by a variety of set criteria. For example, if a certain amount of spam traps are hit or suspected mail spam is received from a particular email/IP address within a certain time frame, an email provider like Google or Hotmail will realise that it originates from a particular IP address. In response to this, they’ll blacklist the IP address and any email sent from that particular IP address will bounce back.

As the spammer shares the host, and therefore the IP address, of hundreds of people, innocent users will be included in the blacklist and be unable to send emails through no fault of their own. This is why it’s so important that the host is able to prevent or quickly remedy any blacklisting as soon as possible.

How does blacklisting affect me?

If your host’s IP address gets blacklisted, any email that you or your company sends will get bounced back by the recipient’s email provider if they’re using the same blacklist.

For an individual, this can be highly irritating. For a company’s marketing department that relies on email marketing to reach a huge volume of customers – this can be much worse. By having your IP address blacklisted can reduce your fancy new online marketing campaign to tatters.

At Fasthosts, we understand just how important it is that the emails of our customers work smoothly without interruption. With our dedicated specialist team, we work proactively to prevent IP blacklisting.

Who’s responsible?

Compromised Hosting Services

It may seem harsh to blame legitimate customers but a large portion of all global spam is caused by the compromise of existing hosting services. For example, a compromised mailbox password or a website vulnerability caused by not updating a third-party WordPress app can lead to exploitation. Once a hacker has achieved this they are free to send spam on their behalf, often in the form of a phishing attack. In many cases, the owner of these services is completely unaware that their services have been used to send spam.

Unwitting marketers

Another cause of IP address blacklisting is when a genuine email marketer gets wrongfully judged as a spammer. A large proportion of marketing emails are flagged as spam because the senders don’t follow so-called ‘best practice’. Examples of best practice include having unsubscribe links on emails or ensuring that all recipients have signed up using a ‘Confirmed Opt-in Process’.

Professional spammers

Nonetheless, the primary reason that IP blacklisting occurs is because of malicious parties who knowingly sign up for hosting services with the sole intention of using a platform to spam. Their usual aim is to send emails that look like they are from another party or organisation in order to harvest personal data or even infect other networks with viruses or malware.

If hundreds of other blameless people are operating from the same server as the professional spammer, they unfortunately have to suffer the fallout when the IP address they share is blacklisted.

To prevent this, at Fasthosts we have a dedicated team with a number of measures in place to ensure that our customers’ emails are always working as they should. The first action performed by the team is initiating a pending signup process so they can check on new accounts that have been opened. This can identify any trends and traits of previous offenders to pre-emptively prevent any issues.

All customers that do sign up are also tracked so that any unusual behaviour is detected so that fraudulent actions are stopped. By sensing any issue early, the Fasthosts team can act to prevent it quickly.

Fighting spam works both ways

Preventing spam is more than just the problem of your particular email host; it’s an issue across the industry. Because of this, companies try to help each other by communicating. If our infrastructure is being used to send spam, we at Fasthosts need to quickly work out where it’s coming from so it can be dealt with quickly. The longer the spam activity occurs, the more this has a negative impact on our server IP reputations which will ultimately lead to blacklistings.

To help us achieve this, we use a number of spam feedback loops from a variety of major email providers, such as Microsoft. These feedback loops provide Realtime notifications when Microsoft recipients mark any email received from our servers as spam. As for protecting our own network for inbound spam, Fasthosts also uses Realtime Blacklists to help us verify that mail received to our network is from a legitimate source, rather than spam.

A key part of how the Fasthosts team reacts so speedily to threats is by listening carefully to our customers. Similarly, the education of our customers on how to adopt security-conscious processes, such as looking after their login information, is vitally important for our team. If you suspect that your domain has been blacklisted by someone, click here to find out.