While you can appeal to these blacklisting services by contacting them, you should first determine whether they have any value to you. To set the baseline, it should be made clear that anyone can create a blacklist and list IPs on it. That, in itself, does not make a blacklist relevant. A blacklist becomes relevant when you need to communicate to someone who uses that blacklist as a means of filtering traffic to their servers. At that stage, you have two options:
- Appeal to the server owner. Are they being excessively picky by using this blacklist to filter traffic?
- Appeal to the blacklist owner. Are they holding an IP accountable for something someone used it for in the past?
In many cases neither will want to speak to you, which leads to:
- Get a new IP address (on our platform that means create a new droplet).
- Use an external mailing platform that specializes in delivery and IP reputation.
The truth is that blacklist owners are both reasonable and unreasonable. Neither is always guaranteed to be true, but it is always one or the other. Some blacklist owners are reasonable and want to speak to you. Some blacklist owners are unreasonable and will speak to no one. Some, even, are creators of extortion schemes who try to get you to pay to whitelist an IP with their service (while no one even uses them to filter traffic) and they get your attention by using "blacklist checking" services to propagate their schemes.
There's no one right answer to any of it, but one thing is almost always true: No one filters your email to spam folders based on blacklists. While IP reputation/warmup may be relevant, blacklists are almost exclusively used to block emails entirely rather than to choose their delivery destination. More important for inbox delivery over spam folder will be:
- Your domain's reputation
- How long your domain has existed
- How long your domain has been using that IP
- Your adherence to the commandments of email, which you can check here: https://www.mail-tester.com/
Hope this helps :)