Some email servers and SPAM filters have lists of IP addresses of known spammers. If a sending IP address is on the list, they won’t let the emails through. Unfortunately, these blacklists also contain many legitimate senders. Just a few spam complaints can land an IP address on a blacklist despite the fact that the ratio of complaints to volume of email sent is extremely low. So even if you are not one of those high volume spammers, you can still get on a blacklist.

Anyone can setup their own “blacklist” for their email server. And they can make the list public for anyone to see and use. So, not all blacklists are created  for the same reason or setup in the same way.  Actually, some irresponsible blacklist owners blacklist IP addresses out of spite. Smaller blacklists like SORBS, blackholes.five-ten and Spam Cannibal have less influence with the more popular, bigger ISPs. Most large ISPs only use the most reputable blacklists. This includes SpamCop, Spamhaus and URIBL.


Why are you on a blacklist?

IPs are most commonly listed on blacklists because email from the IP address is going to spam traps operated by the blacklist and/or end user complaints tracked by the blacklist. To prevent a listing on a blacklist follow recommendations listen below and our recommendations to reduce complaints and spam traps.

A good place to see if an IP address is on a blacklist is at:

You will need to know which IP adress(-es) you are sending from. Carma accounts that sends a large volume of emails will have their own IP addresses in Carma. If you do not know the IP addresses you are sending from please contact Smaller Carma accounts are sending from different pools of IP adresses and we are very careful with which accounts are placed on these shared IPs. Senders with less than excellent sending routines will be placed on IPs with same types of senders. In general, if you are on shared IPs and don’t hear from us you are doing good and should not worry too much.

Tips to avoid blacklists

There are many legitimate reasons for sending bulk email. For example, regular or ad-hoc newsletters to your customers, product, company or sales information that former customers would like to know about, or related partner communications. In ALL cases, however, this communications must be solicited (i.e. “opt-in”), or you will quickly find your email bouncing due to being listed on one or more email blacklists. Unfortunately, customers may also sometimes forget that they opted in to your communications, and report your email as spam! Following are some best practices to avoid this happening to your email communications.

  1. Follow our recommendations about spam traps
  2. Follow our recommendations about complaints
  3. Only send to those who subscribed – How do you personally react if you receive an email that you didn’t sign up to? Not your favorite email, huh.. Therefore make sure that you only send to those who signed up for your emails. Buying, renting, scraping or finding old customers in your database or CRM, or to ANYONE that themselves didn’t sign up for your emails will always be the biggest cause of getting blacklisted.
  4. Give the reason – At the top of your email, indicate why your customer is receiving it. For example, “You are receiving this email because you selected the option to receive our monthly newsletter when you purchased a product from us.”
  5. Make unsubscribing easy – Immediately after the reason, give your customer an easy and quick way to opt out of receiving future communications. For example, “If you would no longer like to receive our newsletter, please click on this link to unsubscribe.” Yes, you can put the unsubscribe link at the bottom of your email, but keep in mind that people will decide to label an email as spam in less that a second. If it is not easy and quick to find the opt-out link, you increase the probability of being labeled a spammer.
  6. Use a known email domain – Sounds obvious, but we know from the emails we receive that it’s not. If customers opted-in to your newsletter while purchasing a product from, then an email from is more likely to be reported as spam, since they don’t recognize the latter domain as a business they have used in the past.
  7. Keep the trust – Trust is arguably the number one issue in eCommerce. Provide a link to your privacy policy in your email, and if you belong to a trusted organization such as the Better Business Bureau, consider placing the trust seal in the email also.
  8. Ensure value – If your emails contain information that the customer finds of value, you will reduce the risk of getting placed on an email blacklist. If you don’t have much value to communicate, don’t send the email!
  9. Watch the frequency – Don’t send emails too often (in your customer’s opinion!). Weekly or even monthly communications may be considered too frequent for some types of communications, while daily may be acceptable for others. Yearly communications sometimes result in customers forgetting they did business with you, and may increase the likelihood of being reported to an email blacklist. Promotional messages should usually be sent less frequently than informative messages (e.g. product sales vs. daily stock market reports).
  10. Ask for feedback – In your emails, ask your customers for feedback on the value of the email content, and any suggestions they have for improvement. If you ask for feedback, however, be sure to reply to it. Ideally, feedback receives a personal reply. At the very least, however, you should have a feedback box with an automated reply. Remember, though, that feedback that appears to be ignored can upset customers which can cause attrition or email blacklisting. Some customers may try to unsubscribe by using the feedback address or link, rather than the unsubscribe link. If you don’t want to be on an email blacklist, you MUST monitor and quickly address any complaint messages or requests for removal. Otherwise, your next email is likely to be reported as spam.
  11. Allow personalization & segmentation – As possible, make it easy for people to change the email address that you use for communications, and select which types of information they wish to receive.

How to resolve blacklists

If the Carma Abuse Team or Carma Support has sent you a link to this page with information that you caused a blacklist listing, make sure to read and understand the following information. Our Abuse Team monitor over a hundred blacklists and if an IP adress gets listed on one of them, we receive notification alerts.
We start by analyzing who caused the listing and try to understand the severity of the listing. An email and/or a phonecall will be made to our contact on your end with information about the IP adress and link to this page.

Please read this carefully:

  • Emails from your account is the reason why you now are on a blacklist. You are the reason of this listing, noone else.
  • Emails can and will be blocked because of this listing. Your deliverability is affected.
  • Even if we help you get off the blacklist, you will soon get on it again if you don’t fix the cause of the listing. Please read “Tips to avoid blacklists” above.
  • Since you are the reason you are on the blacklist, we are not obligated to get you off the list for free.
  • We will help you (ask nicely) but make sure you do your part to avoid getting on the blacklist in the first place.
  • IF your emails are causing severe problems to our system, we might move you to a different IP adress or potentially shut down your account until further notice.
  • Please compare the date and time for when you were blacklisted with the emails you sent during that period to see if there are any differences in your sending routines within the nearest time frame.
  • For more details about the blacklist you are on, find the name of it below and click the link.
  • For help with delisting or if you have any questions, please direct them to

More information on some blacklists


Next: Volume

This is an article in the Carma Campus Class in Deliverability