Finding your IP or domain on a blacklist is bad news for any email program. So what preventative steps can you take to keep from being blacklisted?
We asked email deliverability experts Brad Gurley from Message Gears, John Peters from Campaign Monitor, Laura Atkins from Word to the Wise, Raja Datta from TrueAccord and Chaitanya Chinta from Netcore to help us understand email blacklisting a little better and more importantly, how to reduce the risk of being blacklisted.
Here’s what they had to say…
Bad Subscriber Acquisition & Poor List Management Will Land You In Hot Water
My list of practices that will get you on a blocklist really boils down to two key areas: bad subscriber acquisition and poor list management.
Under the umbrella of bad subscriber acquisition, there are two problematic practices I see again and again:
Sending without permission. This should be known as the cardinal sin of list acquisition. If you paid for the list, scraped it off the internet, borrowed it from another organization, downloaded it from a government database, or obtained it in any way other than the subscriber giving you explicit permission, it will get you blocked. Blocklist operators don’t care whether you have the legal right to send them email – if their users didn’t ask for it, they’ll complain. And when they complain, you’ll get blocked.
Not setting clear expectations (or not sticking to them). When someone opts into your email program, make it very clear what they’re getting, who it’s coming from, and how often they’ll get it. Consistent branding helps recipients quickly identify your email and come to expect it. If you make significant changes to your frequency, branding, or content, you’ll need to communicate that clearly to your recipients (and give them the chance to opt out).
When it comes to list management, there are a few more troubling behaviors I see. These include, but are not limited to:
Failure to honor unsubscribes. Every sender should know this is a huge red flag. This one is illegal in many jurisdictions, so the impact could go far beyond the block list. If someone asks to unsubscribe, make it happen as quickly as possible.
Making it hard to unsubscribe. Many marketers think that by making the unsubscribe link hard to find, or requiring a login or other hoops for subscribers, they’ll decrease the number of unsubscribes — and they might be right! But if someone who wants to unsubscribe can’t, guess what they’ll do instead? Mark your messages as spam, and get you blocked (not to mention that laws like CAN-SPAM explicitly forbid some of these practices).
Put the unsubscribe link front and center! Someone who wants to receive your emails is very unlikely to accidentally unsubscribe, and you’re doing much more damage by making recipients search for the unsubscribe link.
Sending to everyone who’s ever signed up for your emails. This one is a bit more broad because the exact practices will vary for most senders, but you should have a tested, regular method of keeping your subscriber list clean. If you’re sending to recipients who signed up years ago and never opened an email, visited your site, or made a purchase, you’re sending to addresses that will probably get you blocked. Whether it’s spam traps, invalid addresses used as sensors by providers, or new address owners who never wanted your email, what’s on the other end of that outdated email address is likely a shortcut to Blocklist City.
To avoid this, send regular re-engagement campaigns to those in danger of becoming stale. Regularly prompt recipients to update their profile or preferences for email. And use the data you have! Opens and clicks are great metrics, but they don’t always show us the full picture. Use them in conjunction with site visits, purchases, and other signals to determine who’s really engaging with your emails (and help yourself stay off those blocklists!)
Understanding Spamhaus Block Lists (SBL) & More
When Kickbox first asked me this question, I wasn’t sure where to start.
There are hundreds of publicly available blacklists and an unknown number of private ones. So I wrote back and asked if he had any particular list in mind, as there was no rational answer to the broad question other than “whatever the listing criteria is.”
After a little clarification, turns out they were mostly interested in the Spamhaus Block List (SBL).
That’s pretty simple. Spamhaus itself says : “IP addresses are listed on the SBL because they appear to Spamhaus to be under the control of, used by, or made available for use by spammers and abusers in unsolicited bulk email or other types of Internet-based abuse that threatens networks or users.”
In my experience, IPs listed on the SBL get listed primarily because someone at Spamhaus noticed them sending spam.
The SBL is maintained manually and getting listed means someone has looked at mail from that IP and seen characteristics of spam.
Another thing to be aware of is that almost all Spamhaus listings involve mail coming into spamtraps.
Spamhaus maintains an extensive network of trap ‘feeds’ – some of them getting thousands of emails a minute. Being noticed in these feeds means that a human has looked at the feed and determined this is a big enough problem to be listed.
A listed IP is sending more mail to spamtrap addresses than other IPs are.
There is one part of the SBL that is not manually maintained.
The CSS is a subset of the SBL that is programatically generated and primarily lists IPs that show characteristics of being part of snowshoeing.
The CSS is tied pretty closely into the domain block list and often IPs are listed simply because they are sending mail mentioning a domain on the DBL.
Not always, but I have had experiences where a client has tried to delist from either the DBL or the CSS and have been unsuccessful. SBL reps have told me that both listings need to be resolved at the same time otherwise the listings will simply be regenerated.
Overall, the important thing to remember about a SBL listing is they are a sign something is deeply wrong with an email program.
I’ve seen lots of senders over the years with pretty bad practices and some serious delivery problems without a SBL listing.
IPs don’t get listed for a few trap hits, they get listed because the sender is hitting hundreds of traps.
Finally, remember that the only reason SBL listings matter is because hundreds of service providers have decided to trust Spamhaus’ methodolgy and criteria. Spamhaus itself is nearly 20 years old and has a history of being an effective and conservative filter.
Healthy List Practices Will Help Keep Your IP/domain in Good Standing
There are hundreds of blacklisting services out there – some more reputable than others – and these services use a combination of content filters, spamtrap data, machine learning algorithms and abuse teams to determine whether an IP or domain should end up on on their block list.
Many factors are weighed to score the IP/domain, such as:
- the age and location of the IP/domain
- IP/domain reputation and sending history
- the number of complaints made by email recipients
- how many recent messages went to non-existent and disabled mailboxes
- emails sent to subscription bombed mailboxes
- emails sent to spamtraps
- the types of spamtraps emailed
- malicious/illegal content and links sent from/hosted at the IP/domain
- whether the IP/domain sends marketing email
- and many others
If the IP/domain’s score meet or exceed certain thresholds set by the blacklisting service then the IP/domain is added to their list.
Sending or hosting malicious/illegal content, sending to purchased or scraped email addresses, sending to old/unused/poorly managed lists, using unprotected online forms vulnerable to spambot attacks are all practices that can land an IP/domain on black lists.
To avoid your IP/domain traffic from being blocked, I would recommend the following steps:
- Ensure links connect to content you trust and is associated with your brand or business
- Audit all signup sources so they require explicit, direct action to opt in and are protected with Captcha
- Re-engage subscribers who have been on your list between 3 to 12 months and consistently don’t open or click on emails
- Remove inactive subscribers who haven’t taken any action in the last twelve months, such as opened or clicked on an email, made a purchase, or visited/logged on to your website.
Fundamentally senders need to send from domains that their recipients know and trust, and from IPs that the receiving servers know and trust. If you’re having delivery problems it’s important to investigate the cause and work to resolve the issue rather than simply changing theIP/domain. Sudden or frequent changes to your IP/domain could lead to worse delivery issues.
In the end, the habitual implementation of such general list-health practices not only provides you with a good reputation among anti-spam services but also helps you consistently earn your place within your subscribers’ inbox
Common Practices That Will Land You On a Blacklist
Let’s start with collection practices, never purchase a list. Purchased lists can have not only forged or spammy addresses, but the users of these lists never opted into your email and do not have any knowledge they will be getting an email by you which leads them to report the message as spam.
Having a lot of bounced addresses as well can be a hint that users in your list are not opted-in or current.
Various blacklists use spam traps to find spammers.
Avoid sending the same message over and over, subscribers want unique content which keeps them engaged and helps you avoid getting a complaint which blacklists look for.
Spam complaints are a huge factor, if people receiving your email continuously click the spam button it leads ISPs(Internet Service Provider) and ESPs to think either the content or list hygiene is not any good.
The more complaints, the more likely the IP/domain will be on a blacklist.
Another practice that is common are email addresses in your list of recipients who have not opened or clicked a message in some period of time.
This period of time depends on the industry. For my team, after 60 days if a subscriber is not opening an email we sunset the addresses to avoid user complaints or ending up in spam by ISPs.
Configuration, Infrastructure and diagnostic issues finally can also land you onto a blacklist:
- Misconfigured DNS
- Use of a shared IP addresses, which in turn can put your domain on a blacklist. This is usually due to someone else’s bad practices
- Use of common links in your email with links that have been included in “spam” emails
- Improperly formatted emails and/or email headers
- Email sending volume that is not consistent over time
- Excessive use of “spam words”
Blacklists are not around to make life harder, but to help have checks and balances in your email program.
Maintaining Good List Hygiene & Sending Relevant Content Will Keep You Off Blocklists
Every blocklist has its own listing criteria. If an IP/Domain meets the listing criteria, it gets listed in a respective blocklist. Blocklist maintainers usually control the listing criteria.
Some look at evidence of spam-like spamtrap hits or a complaint and some look at potential threats based on similarities with other spam patterns – like age of domains, whois information or domains/IPs under a known spam entity, etc and some blocklists look at the combination of both. Depending on the nature and quality of a blocklist, a positive listing can be a small annoyance to your email program or a complete showstopper.
In order to be safeguarded from getting onto blocklist, you need to ensure that the user signup/ email addition process has enough measures in place. If your signup is a single opt-in or you allow email appends from unverified sources, there is a high chance that your list will be filled with spamtraps and targeting them will end up your IP/Domain in a blocklist.
Implementing a confirmed opt-in, email validation service on the signup form, Social sign-in validation, having a proper sunset policy for old/inactive subscribers will help in reducing the possibility of getting listed in a blocklist.
Maintaining good list hygiene and mailing relevant content to genuine subscribers will ensure that your IPs and domains are in your control and your Email Service Provider will thank you for it.
More Email Deliverability Unfiltered, Next Month
Join us next month for more insight into the hidden, technical aspects of sending email. We’ll delve into the highly nuanced nature of how email gets from sender to receiver, the service providers that exist between and the practices that get you in or out of trouble.
Keep your list healthy and boost campaign performance by regularly cleaning your email list. We’ll let you know which email addresses are good, bad and risky, before you hit send.
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