If multiple hosting clients are claiming that their e-mails are going into the recipient’s spam folder, it isn’t necessarily an issue with their email content. If one or more of the accounts on a shared server is compromised and uses it to send spam messages, infected messages, bulk messages, or other unwanted messages, the server can gain a bad reputation. The reputation issue may also impact legitimate senders as they can have the same IP address as other clients.
This can be a potential issue for hosting providers and resellers. There is a possibility of important emails such as password resets, invoices, contact form messages and business communications going astray from the inbox. The IP address may also be listed in public, real-time block lists (RBLs) in some cases.
Fortunately, many IP reputation issues can be identified and rectified by determining the root cause of the issue and addressing it. Hosting providers can offer a combination of blacklist monitoring, email authentication, account-level controls, server security and improved sending practices to ensure the protection of client’s email delivery.
What Causes a Server IP to Get Blacklisted?
An IP blacklist is a list of IP addresses established by security firms, mail servers and filters to determine if a specific IP address is linked with suspicious e-mail activity.
A server IP may become listed for several reasons:
- Spam sent from a hosting account
- Malware or a compromised website
- Stolen email passwords
- Large volumes of unwanted messages
- Poor email authentication
- Sending to invalid or inactive addresses
- Open relay configuration
- Customers using the server for abusive email campaigns
- Previous users leaving the IP with a poor reputation
A major drawback of shared web hosting is that the IP address is shared. Even if one account is “bad,” potentially other users of the same outgoing IP can have delivery issues.
For instance, a server can have 100 web pages. There are 99 business customers and one customer gets his/her email account hacked and starts sending thousands of spam messages. The server IP might be recognized as having unusual activity, causing email providers to be suspicious of the server email and the information it contains.
That’s why it’s vital for hosting and reseller companies that they monitor emails at the server level.
Check Whether the Server IP Is Blacklisted
If you need to make changes to the configuration, be sure to check if the IP address is included in the list.
First look at the public IP of the server in various reputable RBL and DNS-based blacklist services. Don’t rely solely on one blacklist, as other blacklist providers use different ways of detecting and different policies in listing websites.
Record the following information:
- The affected IP address
- The name of the blacklist
- The reason for the listing
- The date of the listing, if available
- Any removal instructions provided by the blacklist operator
This information helps you understand whether the problem is caused by spam, malware, a compromised account, or another issue.
It is also useful to check mail server logs. Look for unusual spikes in outgoing messages, repeated delivery failures, large numbers of messages sent by one account, or authentication attempts from unknown locations.
If only one client account is responsible, fixing that account should be your first priority.
Find the Account Causing the Problem
A server blacklist does not necessarily mean that the server is blacklisted. One compromised cPanel, one mailbox or one site in many cases is to blame. Review server logs and mail activity for unusual mail sending patterns. When it’s determined what is causing the unwanted emails, secure the account and eliminate the source.
Key Points:
- Check mail logs and delivery reports.
- Find accounts sending unusually high email volumes.
- Look for high bounce rates and unknown recipients.
- Check for repeated login or authentication failures.
- Scan websites for malware or malicious scripts.
- Change compromised passwords and update CMS plugins.
- Monitor the server after fixing the issue.
Fix Server IP Blacklist Email Deliverability Problems
The first step in solving email deliverability issues when an IP address is on a blacklist is to determine where it is coming from and to take measures to protect the affected person’s account or site from the spammers. Replace any compromised passwords, remove malware, update software and look at the mail server configuration to make sure that it is not set up as an open relay. Check SPF, DKIM and DMARC records and enhance email authentication.
Once the root cause is resolved, review and verify the provider of the blacklist and the process of removal and request the delisting if necessary. Do not ask to be removed during this time period when spammers are still posting spam, or the IP number will probably be added back. Periodic checks also can stop any future blacklist issues and keep the server’s email reputation intact.
Set Up SPF, DKIM, and DMARC Correctly
Email authentication allows the recipient mail servers to check the message’s authenticity. SPF will tell mail servers who are permitted to send email from your domain, DKIM adds a digital “fingerprint” to the message, and DMARC will instruct mail servers on what to do if email fails to be verified.
Properly set up all three can enhance email trust, minimize spam, and assist web hosts track illegal email activity.
Key Points:
- Add one correct SPF record for each domain.
- Configure DKIM and publish the public key in DNS.
- Set up DMARC to monitor authentication failures.
- Review authorized email-sending services regularly.
- Fix SPF, DKIM, or DMARC errors quickly.
- Use authentication reports to detect suspicious activity.
Consider Dedicated IP Reputation for Important Clients
If you are using shared IPs you run the risk of email reputation issues as the activities of one customer can impact another, both on the same IP address. Use of a dedicated IP provides businesses greater control over their email reputation, and can be beneficial for significant transactional or marketing communications. But it’s still important to be able to properly authenticate, secure, monitor and send responsibly through a dedicated IP.
New IPs must also slowly establish their credibility, as opposed to sending out huge volumes of e-mail right off the bat. Hosting Providers and Resellers must take care of the dedicated IP reputation, as it’s crucial to ensure client email delivery, and to minimize the chance of spam related reputation issues.
Handle RBL Blacklist Removal Carefully
Before realizing that the listing information is regarding your IP address, read the information listed on the RBL.
Each blacklist provider has their own requirements. Some will concentrate on spam traps, others on complaints, spam and/or odd mail behavior.
If you need RBL blacklist removal for a dedicated IP, follow this general process:
- Identify the exact blacklist.
- Read the listing reason.
- Find the source of the unwanted email.
- Stop the abusive traffic.
- Secure the affected account.
- Check the mail server configuration.
- Confirm SPF, DKIM, and DMARC.
- Monitor outgoing email.
- Submit the removal request if required.
- Continue monitoring after removal.
Do not assume that getting removed from one blacklist means the overall problem is solved. Check other major reputation sources as well.
Prevent cPanel Client Emails Going to Spam
Hosting administrators looking for cPanel client emails being delivered to the client’s spam folder probably shouldn’t focus merely on the cPanel interface.
cPanel also allows mail accounts, authentication, DNS settings, and server-side email operations, but it doesn’t handle email delivery-only the receiver’s email provider.
The first thing to be checked is if the client domain has a valid SPF and DKIM record. Afterwards, confirm the DMARC configuration.
Then check the logs on the server for any strange activity in its mail logs. Investigate it right away, if one account is producing a lot of e-mail.
See if clients are sending e-mail to obsolete or bad e-mail addresses. If you have a lot of bounced messages, this will negatively impact sending reputation.
Clients should avoid practices such as:
- Sending unsolicited bulk email
- Using purchased email lists
- Sending identical promotional messages repeatedly
- Hiding the real sender identity
- Sending from compromised accounts
- Using misleading subject lines
In addition, reasonable limits should be set on the amount of email sent out by email host providers. With rate limits, it will minimize compromised account harm.
Monitor Outgoing Email Traffic
The earlier the suspicious activity is observed the easier it is to prevent.
Enable monitoring of volume of outgoing emails and unusual activity on the accounts. If any of your email suddenly becomes more voluminous, then it is the reason for an investigation.
Useful metrics include:
- Messages sent per hour
- Messages sent per account
- Bounce rate
- SMTP authentication failures
- Spam complaints
- Delivery failures
- Blacklist status
- Mail queue size
Monitoring will help to detect the compromised account, before the IP reputation gets severely tarnished.
For hosting providers with numerous customers, automated alerts are particularly beneficial. Rather than having to wait for clients to start complaining that their email is ending up in the spam folder, administrators can look into weird behaviour as soon as it occurs.
Improve Server Security
The reputation of email is closely related to the reputation of the servers. A compromised website, CMS plugin, mailbox, or control panel account can become a source of spam. Keep the operating system, control panel, CMS software, plugins, and security tools updated.
Using dedicated IP addresses can also help hosting providers maintain better control over their email-sending environment and monitor the reputation of individual IPs. Secure administrative user passwords and, if possible, use multiple authentication methods. Also, eliminate unnecessary services and check server logs frequently.
Use a Reliable Dedicated Server for Better Control
Hosters with critical websites and email workloads may find infrastructure that provides them with a better level of control over resources, security and network configuration to be beneficial.
Isolated use of the CPU, RAM, storage, and network resources can be made possible with a dedicated server. It can also enable custom monitoring and security policies to be easier to implement.
If you are looking for infrastructure for hosting workloads, a cheap Linux dedicated server can be a practical option when Linux-based hosting tools and server-level control are required.
But hardware isn’t the only thing that will lead to improved email delivery. The proper configuration, authentication, security, monitoring and responsible use of DNS is still vital.
Create an Email Abuse Response Process
Hosting providers must have a procedure in place for blacklisting of servers and receiving of a spam complaint. Speed in pinpointing the source, halting suspicious use, securing compromised accounts and verifying email authentication can help prevent damage to the reputation of the server.
Once the problem has been resolved, follow the blacklist provider’s removal procedure and keep a close watch on email traffic, so that the problem doesn’t recur.
Key Points:
- Identify the affected server IP.
- Check logs to find the source of suspicious emails.
- Stop or restrict abusive accounts.
- Reset passwords and remove malware.
- Verify SPF, DKIM, and DMARC settings.
- Check RBLs and email reputation.
- Request blacklist removal after fixing the cause.
- Monitor email traffic regularly.
How to Prevent Future IP Blocklisting
Removal of an IP from a blacklist is only the first step. Hosting providers should focus on preventing the same issue from happening again.
Set reasonable outgoing email limits, monitor unusual mail activity, and keep client websites and passwords secure. Regularly check SPF, DKIM, and DMARC records, especially after DNS or email provider changes.
For important business emails, separate email infrastructure may provide better protection. Most importantly, detect and restrict compromised accounts quickly before they damage the reputation of the entire server.
FAQs About Server IP Blocklists and Email Deliverability
Q: Why does a server IP get blocklisted?
Servers can be blocklisted because of spam, compromised email accounts, high bounce rates, or other suspicious activity. On shared hosting, one client’s actions can also affect the email reputation of others on the same IP.
Q: How can I check if my server IP is blocklisted?
You can check your server IP against reputable RBL and DNS-based blacklist services. If it is listed, identify the reason, find the source of the problem, and follow the provider’s removal process.
Q: How do I remove a server IP from an email blacklist?
First stop the spam activity and secure the affected account or server. Then fix authentication or configuration issues and follow the blacklist provider’s official delisting process.
Q: Can SPF, DKIM, and DMARC improve email deliverability?
Yes, properly configured SPF, DKIM, and DMARC help receiving mail servers verify legitimate messages. They can improve email trust and reduce authentication-related delivery problems.
Q: Is a dedicated IP better for email deliverability?
A dedicated IP provides greater control over email reputation because it is not shared with other customers. However, proper authentication, security, monitoring, and responsible sending are still essential.
Wrapping Up
If your hosting clients host multiple email addresses on the same IP address, your email delivery can be significantly affected if the server IP is added to a blocklist. When one of the websites, mailboxes or hosts is compromised, it can harm the reputation of the entire server.
To mitigate this risk, the hosting provider needs to locate the origin of the unwanted mail, isolate the compromised account(s), clean up the malware and properly set up SPF, DKIM and DMARC.
Problems can be identified in a timely manner through regular monitoring of the following: outgoing email traffic, bounce rates, mail queues and blacklist status. Also, host providers ought to utilize robust safety measures and sensible email limits for their clients’ accounts.
