When you purchase a plan from a hosting company, you will be given an allocation of resources. If you have a shared hosting plan or VPS hosting plan, you will be given a share of a server's storage and resources, however purchasing a dedicated hosting plan gives you full control over the server.
Regardless of what hosting plan you purchase, you will be allocated an IP address. It is important to check the reputation of that IP address when it is allocated to you as it could be blacklisted.
Blacklisted IP Addresses
IP addresses can be blacklisted if they are known to have malware or if they have been known to be the source of spam email. This can affect your website traffic and it can greatly effect the delivery rate of emails that are sent from your website or server since email services use blacklists. It could, for example, stop verification emails being received by those who create a new account on your website.
Domain names can also be blacklisted if they have been found to be the source of malware of malicious content.
It is not always the fault of the website owner if their IP address or domain name is blacklisted. It can happen to anyone.
For example, a number of years ago a small content website I had forgot to update to the latest version of WordPress had been compromised. This allowed spammers to upload a script that send thousands of spam emails from my server. As a result of this, only a small percentage of emails being sent from my websites were actually being delivered.
You should check the reputation of your IP address when it is initially allocated to you, however it should also be monitored on a regular basis since an IP address can be added to blacklists at anytime.
If you purchase a shared hosting plan, the odds of an IP address being blacklisted are higher because hundreds, or perhaps even thousands of other website owners, will have the same IP. It is less likely if you have a VPS or dedicated hosting plan since one or two unique IP addresses are provided to each customer.
If you are unfortunate enough to be allocated an IP address that has been blacklisted, ask your hosting company to provide you with a new one. A good hosting company will be apologetic about giving you a blacklisted IP address and will resolve the issue quickly.
As you shall see, IP addresses can be easily removed from blacklists, but I still do not believe that any hosting customer should accept a blacklisted IP; particularly as it could be weeks before the IP is clean. If a hosting company refuses to provide you with a clean IP address, take your business elsewhere.
How to Monitor Your IP Address and Remove It from Blacklists
There are a number of great services online that help you check whether an IP address has been blacklisted.
The service that I have used for years is MxToolbox. They offer a wide variety of monitoring services including blacklist monitoring, DNS monitoring, SMTP monitoring, and more.
The free plan offered by MxToolbox checks one IP address or domain every seven days against thirty blacklists. Upgrading to their basic plan at $20 per month allows you to check up to ten IP addresses or domains every four hours against over one hundred blacklists. Additional features are included with this plan.
Their pro plan costs $80 per month and grants access to their API and telephone support for delisting.
If all of your websites are hosted on the same IP address, you should be content with the free plan offered by MxToolbox. They will email you updates once a week advising you the status of your IP address and you can do a check against blacklists on their website at any time.
As you can see from the screenshot above, the check against popular blacklists showed that my IP address was not listed on any blacklists. If my IP address was listed, I would need to investigate the situation further.
The first step is to check your server and make sure that it is secure. Any malicious scripts that have been uploaded to your server will have to be removed. You can use tools such as Sucuri's website scanner to test if any malware or spam is present.
Speak to your hosting company if you are unsure about how to check for malware on your server. They should also help you to harden your server and explain how hackers compromised your website.
Blacklist monitoring services such as MxToolbox provide detailed instructions on how you can remove your IP address from these lists. Most blacklists require you to enter your IP address directly on their website. Some may ask you to sign up in order to do this.
It is worth noting again that you should not attempt to remove your IP address or domain from any blacklists until you are 100% sure your server is safe and the malware and spam has been removed.
It can take days or weeks for blacklists to update their databases to show that your IP address is safe. Once they have updated their list, your emails should start be received as normal.