Many a times it is found that users sending legitimate email messages are blocked from sending them because the IP address supplied to them by their Internet Service Provider (ISP), is on some major blacklist. While the major ones will de-list IP addresses after a few hours or days, if there has been no serious continuing activity, others may block not just a single IP address but a series of 255 IP addresses that are "near to it", depending upon the severity of the spam transgression.
An IP blacklist is a real-time database that uses set criteria to determine if an IP is sending email that could be considered spam. If an IP address is on the list, they don't allow your email through. There are several blacklists including Spamhaus, Barracuda Reputation Block List, and SpamCop to name a few, but they all have their own criteria for accepting inbound mail and all can have a negative effect on your delivery rate.
You may ask that I am sending emails through Batoi, whose servers are not themselves on any blacklists, still my emails are bouncing back. Why so?
When you send an email message, part of the message i.e. the "Email Header" contains information about message such as the subject, sender, recipients etc along with a set of "Received" lines that document the path the message took through the Internet, as it transits from you to your recipients. This set of "Received" header lines provide a kind of "Audit Trail" that allows anyone to look and see where the message travelled and where the delays occurred. The first "Received" header line contains information about the outgoing mail server to which the email program on your computer connects; it records that it got the message from you and at what time along with the IP address of your computer as provided to you by your ISP. If the spam filters find that your computer's IP address is on a blacklist and that IP address is recorded anywhere in the message headers, they can block your email.
There are over a hundred SPAM blacklists private corporate spam firewall and private blacklists, but luckily there are a few tools that can help you check most of them quickly. We have included here a handy reference with the sites that you can use to check your blacklist status.
High spam complaint rates are one of the main reasons why your IP ends up on a blacklist. So it is imperative that once you discover that you are on one, that you take steps to get your IP removed from the list. By visiting each of these sites, you can enter your IP to check your list status, and then obtain instructions on how to be removed. The key here is to be proactive.
Updated on Nov 11, 2015
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