Why do mail servers get blacklisted?
In this article I'm going to breifly explain why it's common for mail servers to get blacklisted, and what you can do if your own server has been blacklisted.
What is a blacklist?
Depending on who you ask, most people who attempt to track the global level of spam being sent, estimate anywhere between 80%-95% of all email transmitted daily on the Internet is spam.
That means that simply relying on manually going through all of your own email, is not the most efficient method for weeding through spam messages anymore these days.
As such there are published public blacklists of mail servers that have been relaying spam. This allows other mail servers to first check if they're receiving an email from a server's IP address that might have possibly been flagged for sending spam in the past.
For instance you can use our blacklist check tool to check if your server is currently listed on any public blacklists.
Why is my server on a blacklist
It's not very uncommon for a server's mail IP address to temporarily end up on a public blacklist, especially if you're on a shared server. It could be because of the overall volume of mail that is coming from that server, messages seem to have characteristics of spam in them, or a few other factors as well.
One common cause for getting blacklisted can be with the use of email forwarders. For instance if you have the user firstname.lastname@example.org, and you're forwarding all of your email to a email@example.com account. If someone spams your firstname.lastname@example.org address, our mail server could then attempt to forward that onto Yahoo, and their servers might see our mail IP address as relaying the spam message to their server, even though it wasn't the originating server of the spam.
Working around blacklisting problems
Our system administration team monitors our email queues for signs of delivery issues with major email providers. If you're having an issue emailing a certain provider and you need to get a message sent out urgently I would recommend following the steps in my guide on sending mail via Gmail when server IP is blocked to still get your message out in a timely manner.
After that, typically you'd want to request to have the mail server's IP address de-listed from any blacklists that it's currently on. In order to do this you can read my guide on requesting a delisting from a blacklist.
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