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What does it mean when Support tells me my IP address is on a blocklist/blacklist?

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What does it mean when Support tells me my IP address is on a blocklist/blacklist?
3Essentials protects itself from known spam sources by subscribing to two widely used "blocklists": and These services identify IP address in use by spammers who flood the Internet community with unwanted/unsolicited commercial email. By subscribing to these services, our mail servers get that list and will reject any mail coming from those IP addresses. If you're reading this article, the assumption is you were directed here because you experienced a problem with mail delivery, and 3Essentials Support team has told you your IP address was on one of these blocklists.

But I'm not a spammer, how did I end up on the blocklist? When any any email traverses the Internet, the IP address of every system that touches the mail is appended to the "mail header", showing the path the the mail has taken. This includes the IP address of your computer as you're connected to the Internet, sending the mail message. So, if you send an email to a 3Essentials domain from a account, even though it was yahoo's mail servers that delivered the mail to us, your computer's IP address was still stamped in the header. Our mail servers check every ip address in the header against the blacklist.
What typically will happen is, your Internet Server Provider (ISP) assigns you a dynamic IP address for your Internet connection... for instance, today you might have, and tomorrow you might have this means that before YOU had that IP, some OTHER customer of your ISP had this IP address. Assuming you are not the spammer, it was him/her (someone who had the IP prior to you) that actually conducted some email/spamming activity that caused the blacklist organization to list the IP... and now you're suffering the consequences.

Ok, but I still need to send mail - how do I get off the blacklist? Well. the first thing you should do is notify your ISP of the situation - make sure you provide them the IP address that we identified as being blocked - this will allow them to investigate who used their service in such a fashion.
Next, you need to change your IP, so you can continue to send mail... this will vary from ISP to ISP, but with most broadband services, rebooting your cable modem (or DSL modem) will result in you obtaining a new IP. We advise you to check with your ISP on this procedure though, as 3Essentials is not familiar with your ISP, your equipment. If you choose to reboot your modem, you do so at your own risk, and cannot hold 3Essentials responsible for unintended consequences.

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