As the medium of communication evolves, so is the marketing world. Businessmen keep on taking advantage of the internet as their campaign vehicle. Through online marketing campaign, targets can receive emails – promotion, updates, etc in just a moment. Internet marketers were free to send newsletters to as many recipients as they wanted not until blacklisting issue came to exist.
Blacklists are lists of addresses believed to send spam (unwanted and unsolicited messages sent by unethical marketers). These lists are maintained by certain individuals and groups who monitor the internet for spam reports. They then compile the IP addresses or the domains of those sources reported as spam senders.
Since spam is unlikely and never productive, email users want to exclude this from their inboxes. Because of users demand for a clean mail box, major ISPs and mail administrators look for a blacklist to meet their users need. Once you're IP or domain address is included in the blacklist your email messages will not reach your prospects' inboxes unless you apply for whitelising.
The main drawback of a blacklist is that some innocent senders are included on it, thus legitimate emails from legitimate senders are blocked. Marketers face blacklisting dilemma in terms of sending opted in promotional and news reports for their clients. Spam filters block their messages because their domains are included in the blacklist used by their clients' mail administrator. You can be blacklisted if you have sent a legitimate message in the past which was flagged as spam.
Spam filters check messages based on subject line, content, html code, etc. Your message can be flagged as spam even though you are a CAN SPAM compliant if you fail to take into consideration content assessment of your message.