8 Ways to Secure Your Email Server to Protect Your Company from Data Leaks

There comes a time for every company when your staff will handle proprietary data. As this sensitive data accumulates over the life of your company, a data leak can be extremely detrimental. Through a leak, the information of your customers or patients can bleed out onto the Internet for nefarious characters to steal and sell. How do you protect your company’s email server data?

Here are 8 methods for securing your email server:

  • Encrypt IMAP and POP3 connections with TLS
  • Add DKIM
  • Use SURBL
  • Turn on SPF
  • Get on a DNSBL
  • Run a reverse DNS check
  • Keep server connections limited
  • Change email relay settings

If some of these abbreviations are leaving your head spinning, don’t worry. Ahead, we’ll elaborate on all 8 tips for a more secure email server setup in Dallas. With email data leaks a big news story every few months, you can make sure your company isn’t the next victim!

8 Tips for a More Secure Companywide Email Server

Encrypt IMAP and POP3 Connections with TLS

IMAP is short for Internet Message Access Protocol. It’s considered a standard Internet protocol that allows you to retrieve messages in your inbox if you have an Integrated Circuit (IC) or a Transmission Control Protocol (TCP) connection. Post Office Protocol or POP3 is similar, except it uses an application layer.

The problem with IMAP and POP3 is that neither protocol is particularly secure, not requiring much in the line of authentication. Since Microsoft Excel uses IMAP and POP3, it’s not a good idea to send nor receive unencrypted messages on either protocol going forward. Authenticating with SSTLS will increase the reliability of your outgoing and ingoing emails so you can do business with better peace of mind.


DomainKeys Identified Mail or DKIM is another means of fortifying your company’s email server from data leaks. DKIM will keep your business inbox free of spam and phishing, or at least reduce the instances of these kinds of dangerous spoofing messages.

How, you ask? DKIM lets you verify that the domain that an email sender is claiming to use is indeed theirs. The authentication protocol will assign a digital signature that’s connected to a domain name whenever emails go out on your server. Then it’s just a matter of researching a Domain Name System (DNS) public key for a valid signature. 


The Spam URI Real-Time Block Lists or SURBL will become a valuable tool for your business as well. This spam-blocking solution reviews the links inside an email, looking for links that are deemed malicious or invalid. Then, SURBL will block those emails before they ever reach your inbox.

If you’re especially busy, you can accidentally click a dangerous hyperlink in an email, which then opens up your company to phishing and/or malware attacks. When your company is phished, you could have information such as account numbers, credit card details, and usernames and passwords stolen, both the sensitive info of your internal staff as well as that of your patients or customers. Malware attacks can destroy your computer or your network from the inside out through adware, spyware, ransomware, Trojans, worms, and viruses.

Turn on SPF

No, we don’t mean SPF as in sun protection factor. Instead, we’re referring to Sender Policy Framework. This form of SPF is a method of authenticating emails that can tell when a sender is forging or spoofing an email address. This is good, because it’s not always easy for us people to be able to do the same. Spoofers are very smart these days, and even fake forged email addresses can look quite legit at first glance.

For best results, make sure you’re using DMARC with SPF. DMARC is Domain-Based Message Authentication, Reporting, and Conformance and offers you protective measures against email spoofers. This can limit cyber threats, email scams, phishing, and compromising attacks that can wreck the integrity of your business.

Get on a DNSBL

We’d recommend a DNSBL as well, which is a Domain Name System-Based Blackhole List aka a Domain Name System Blacklist. You might also see this service referred to as a Real-Time Blackhole List or an RBL. The DNSBL utilizes DNS to determine if the IP address sending your company an email is blacklisted for spamming.

The best thing about a DNSBL is it can review more than one list at the same time. Worldwide DNSBL servers can offer your company even more widespread protection. Without spam emails interrupting your day-to-day operations, you can rest assured that your company data is safer. This will help your company maintain customer satisfaction.  

Run a Reverse DNS Check

Speaking of DNS, a reverse DNS lookup or rDNS can also be of great use to your company to limit data leaks. A reverse lookup on the part of the DNS confirms if the IP address and domain name are related via PTR records. This is a pointer DNS record. rDNS will also comb through registrar tables and registries.

Through rDNS, you might be able to learn who a spammer is that’s sending your company unwanted messages. Should someone attempt to hack your company’s network or turn off your firewall, rDNS might also tell you that computer’s domain name. You can discover the IP’s Internet service provider as well.

Even though the information available to you through an rDNS search isn’t always as specific as a first and last name, having any trackable data on a hacker or spammer is better than none, as you’re one step closer to figuring out who this nefarious character is and putting an end to their behavior.

Keep Server Connections Limited

If yours is an SMTP or Simple Mail Transfer Protocol server, you especially don’t want a lot of connections to the server all at once. These servers are frequent targets of denial-of-service or DoS attacks, a type of cyberattack where your network or computer service is disrupted, sometimes on a short-term basis and other times permanently.

Your server is also susceptible to a DDoS or distributed denial of service attack. During a DDoS attack, the cybercriminal sends such a large quantity of data to your computer network that it can’t function anymore. If your company servers are regularly jam-packed, then it can be very hard to recognize when a DDoS attack is happening.

If your company is especially large, we recommend limiting who’s on the server at once, perhaps through shifted work. Your email server will be more robust for it!

Change Email Relay Settings

Most SMTP servers have open mail relay set as a default. With an open mail relay, the server allows anyone and everyone with working Internet to message your server, known and unknown users alike. Spammers, hackers, and other bad apples can easily exploit open relay settings and cause catastrophe for your company.

Go into your email server and ensure that open relay is off, or, at the very least, set up some IP parameters so that not every email can get through. Your IT team can help you change your email relay settings if you’re not sure how it’s done.


The protection of proprietary company data is paramount in your office. All it takes is reading about a data leak to remind you why it’s so necessary to batten down your network hatches and keep spammers and hackers out of your email inbox.

The above methods are great options for safeguarding your email server setup in Dallas. Just because you’re using methods and protocols that will protect you doesn’t mean that common sense should fall by the wayside though. If you don’t recognize an email sender, then reconsider opening the email. Use an antivirus or an attachment checker before opening any attachments sent to you.

A well-functioning, protected email server will maintain your customers’ trust in you and keep your company’s name from being dragged through the mud with bad press. It’s time to prioritize your email server security today!

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