Blacklisting is a term that applies to the practice of identifying email spammers. Spammers are identified based on the IPs and domains they send emails from. This information is compiled into a list that email servers reference, which can block emails from those IPs from being delivered to their intended recipients.
It is estimated that anywhere between 80-95% of all emails sent daily are spam. Because of this, it is unrealistic to assume you can go through and detect spam on your own. Blacklisting helps prevent spam from reaching your inbox and helps maintain email as an effective tool on the internet.
While blacklists are intended to catch harmful spammers and prevent their messages from reaching their destination, anyone has the potential to get blacklisted. Blacklists frequently make mistakes and mark legitimate users as spammers based on their email sending habits.
How do blacklists work?
Internet service providers (ISPs) use a variety of tools to filter incoming email. They oversee all IPs and domains that send out email campaigns and create a sheet, or blacklist, which they can use when evaluating email senders. When you send an email, your IP address is logged—think of it as a return address on a letter’s envelope. This allows mail servers to learn about who is sending an email, and check if the sender has a good or bad sending history by checking blacklists.
How do you get blacklisted?
If you were to send out an email campaign to an outdated list or a list with purchased, scraped or third-party contacts, the servers where your emails are originating from could temporarily become blacklisted. Blacklistings occur by detection from email spam traps, which serve the purpose of detecting spam emails.
There are two types of spam traps. Recycled spam traps are email addresses that were once valid but have since become repurposed by their provider to detect and track spam. Any email address that has not interacted with emails in over a year can become a recycled spam trap. Pure spam traps are often placed in publicly available web pages and on the lists of data providers. They are placed in such a way that normal users cannot see them. These spam traps can only be collected through scraping methods, so they report on senders who are scraping and emailing contacts without opt-in.
Furthermore, if a server is not properly configured, spammers can use the mail server to send out their messages.
Common Triggers that Lead to Blacklisting
- A surge in email volume from your domain can indicate possible spammer behavior.
- High spam complaints that are above the accepted threshold.
- Sending messages to dormant emails, inactive emails, recycled spam traps or pure spam traps.
- Bad content.
How to Prevent from Getting Blacklisted
Here are some common guidelines to follow to avoid getting blacklisted:
- Respect user contact permission levels
- Only send out content that is meaningful and relevant to your recipients
- Regularly remove old email addresses from your contact list
- Do not use blacklisted affiliate links in your campaigns
- Do not send emails too often
How to Determine if you are Blacklisted
While blacklisting has consequences, the ramifications are usually temporary. After some time, you usually will be removed, and the effects are not lasting.
You can monitor your email server reputation by checking blacklists online. ISPs should be doing this on your behalf, but it does not hurt to do it yourself as well. You can use tools such as Mxtoolbox to determine if your server is listed on any open relay blacklists.
Bonus: You may also have heard of the term greylist. These are lists that identify bulk email providers. Private domains can block these lists if they do not want to receive any email marketing. These lists do not typically have any negative consequences and do not affect email delivery.
How to remove yourself from being blacklisted:
Once a server is on a blacklist, there is a lengthy removal process. If you determine that your email server is on a blacklist, you can perform the following process for removal:
- Ensure your server is configured to the best relay settings as suggested in the Article ME020001 and not an open relay
- Check that your server is not being abused by making sure that the SMTP and MTA logs are not larger than usual, SMTP outgoing mail queue is not full of outgoing messages waiting for delivery, valid emails are delayed, etc. Review Article ME020339 for more information.
- Go to the websites of each Blacklist provider and submit your site for removal. Processing your request sometimes takes a long time.
Blacklists to Keep an Eye On
There are a lot of blacklists operating around the world. Some of them are publicly managed and others are privately managed. Not all blacklists have the same influence as others though. Here are some of the most prominent blacklists that you should keep an eye on:
- Spamhaus: It is the most reputable blacklisting company worldwide. Being listed by them has a large effect on email delivery.
- SURBL: This blacklist indexes spam.
- Baracuda Reputation Block List: A type of spam filter that blocks bot-based spam effectively.
- Spamcop: A human-based complaint aggregator that lists reported spammer IP addresses.
Now that you understand what email blacklisting is and how it works, you can see how important it is to maintain the reputation of your email servers. While email service providers do monitor this for you, they cannot prevent you from being negatively perceived by your recipients and marking you as a spammer.
It is up to you to maintain the reputation of your brand. You can choose to manage this yourself by following the blacklisting best practices mentioned in this article or leave it to the experts, like us at FrescoData.
Email marketing is our area of expertise. We follow a variety of different standards to ensure we follow email best practices. The emails from our data lists are not sourced through scrapping. Our private servers are also regularly checked and secured so they will not get blacklisted. We format the content of email campaigns to not appear as spam as well and avoid specific keywords that trigger spam filters. Plus, we can guarantee a 99% deliverability rate when we manage your email campaigns.