Blacklist impact
Blacklists typically occur either on the sending domain, the IP(s) which are being used or a combination of both. This means that if you are using your corporate domain and you get blacklisted due to an issue with a bulk mailing, all of the systems that are using that domain to send any type of email might be blacklisted for an unknown amount of time.
Depending on where you get blacklisted the impact might differ:
- If you are blocked by an individual provider (for instance Hotmail), the block will stay limited to the Hotmail domains.
- If you are on the blacklist of an anti-spam solution (for instance Spamhaus), you will be blocked by the majority of the notable providers. Depending on your list, this might mean that even up to 90% of your company’s emails will not be accepted for delivery.
- Please note that providers and anti-spam solutions work closely together. If you get blocked by for instance Hotmail and the reason for the block is severe enough, you might end up on the blacklist of the anti-spam solution as well and thus on the blacklist of a wide range of providers.
Reason for blacklisting
Blacklist can occur for many reasons. Here are some of the most common issues which can cause blacklists:
You’ve been sending to too many inactive users due to poor quality of your lists. This could be due to an improper handling of incoming bounces or mailing to old addresses that haven’t received any email from you for quite some time.
The users you’re mailing to aren’t expecting your email and/or don’t like the content. Therefore they mark your emails as spam, which is one of the more important signs a providers can get that something isn’t right and your domain/IP reputation will go down. If they see complaints coming in regularly for certain mailings they will eventually blacklist your IPs and/or domain.
You’ve been mailing to spamtraps. Spamtraps are typically used by providers to check whether you’re actually mailing to users who have subscribed to your emails and really want to receive them. The most common types of spamtraps are spamtraps created from inactive accounts and so called honeypots.
- Providers turn old, inactive addresses into spamtraps to check if a sender manages the quality of their lists properly. By the time the address is turned into a spamtrap you should've had plenty of time and received plenty of bounces to unsubscribe the user.
- Honeypots are email addresses that were never actually operated by a human being. These addresses are hidden inside websites for instance, not visible to the normal user’s eye. If these addresses receive email that means they’ve been “scraped” of a website by an automated process and no one ever gave permission to send mail to that address. Hitting honeypots will result in blacklisting in no time. These types of spamtraps are often found in purchased lists.
- Spamtraps are unidentifiable. There is no way to recognize them and no warning will be given when mailing to them. The only way to secure your system against spamtraps is by sticking to the best practices, never using 3rd party lists, apply a sunsetting system and always using a double optin system.
How to mitigate blacklists
Every provider or anti-spam solution has its own rules when it comes to mitigating blacklists. Some are quite easily approachable and will remove a blacklist when they see you’re putting in effort to improve the situation, others are impossible to contact or will not remove the blacklist if there is any reason for them to believe the blacklist should stay in place. It also depend on the reason for the blacklist. For instance, in most cases a blacklist due to spam markings will be more easily removed than a blacklist due to honeypot spamtraps. You never know how long it’ll take and even IF they will remove a blacklist.
