Category Archives: How to Make the Most of MxToolbox

How can I make full use of my MxToolbox account? Part 4, DNS

This is the fourth in our series of making the most of your MxToolbox account.  Today, we’ll discuss DNS tools that make it easy to see your DNS configuration.


DNS is the backbone of the internet.  If your DNS is not setup properly, no one will find you dns_exampleonline, send you email or be able to access your online store.  Checking DNS is incredibly important, so MxToolbox has created a number of lookups dedicated to checking your DNS configuration.  All of these are accessible from our SuperTool interface.

  • DNS (Name servers) – Check your DNS name servers for configuration issues.
  • DNS Propagation – Check DNS records across your name servers to verify they are propagating when updated.  DNS Propagation has its own page.
  • A, MX, CNAME, TXT, etc – Check individual record types to ensure they are setup and responding correctly.

If you want to know more about DNS, there are many resources on our blog.

Our next installment in this series will go over Website lookups for HTTP/HTTPS.

How can I make full use of my MxToolbox account? Part 3, Email

This is the third in our series on making the most of your MxToolbox account.  Today we’ll talk a little about email troubleshooting and what results you can receive from MxToolbox email lookups.


As our name implies, MXToolbox started as a company dedicated to helping customers with email.  We continue that with our large number of email related tools and lookups.  There are several things you can do with our tools:

Test your Email Server’s DNS Setup

To receive email, you need to have MX records setup for a domain.  These can be setup to point to your ISP’s email services, a third-party email service like Gmail or or even an email server sitting in a backroom at your office.  Regardless, you need to make sure your MX records are properly setup or no email will find it’s way to you.   You can test you MX records with the MxToolbox SuperTool.

Test if your Email Server is ready to accept emailsmtp_example

Once your email server is online, you need to test it to see if it is accepting email.  Our SMTP test gives you multiple subtests to on your email server, including:

  • Open Relay – Whether or not your server is an open relay.  It should not be.
  • Reverse DNS Mismatch – DNS matches the IP address and there is PTR record pointing back from the IP address to the domain.
  • Valid Hostname – Checks that reverse DNS is a valid hostname for the DNS.
  • Banner Check – Checks that reverse DNS matches the SMTP Banner.
  • TLS – Checks that the server supports TLS encryption.
  • Connection Time – Checks connection time.
  • Transaction Time – Checks total transaction time.

Email Deliverability ReportLookup your Email Deliverability Settings

Once your email server is up and running and accepting email, the next question is will your email be accepted by your customers, partners and vendors.  Email delivery can be a challenge for companies, especially small companies getting started.   MxToolbox has several lookups that can give you insight into whether your email is deliverable or if your deliverability configuration is working beyond the basics of “Am I on a blacklist?”.

  • SPF – Check your SPF configuration, which specifies which servers are able to send from your domain.
  • DKIM – Verify that you DomainKeys Identified Mail setup is correct and accessible.
  • DMARC – Check your DMARC configuration to ensure that others can read it and send you rejected email from your servers and validate email coming from you.
  • Email Deliverability – See if your domain is on an email delivery problem list.

Analyze Email Headers

Sometimes email seems to work properly and yet a message takes days to arrive.  Sometimes you need to analyze a message to makes sure your system is processing everything correctly or investigate a suspicious email.  MxToolbox created a handy email header analyzer just for that purpose.   Header Analyzer takes your email headers and runs a complete analysis of hops, delays, and important email delivery information.  Use it to decode email delays!

In next topic of this series, we will discuss using DNS lookups.

This is the second in our series on making the most of your MxToolbox account.  Today we’ll talk a little about blacklisting. 

Blacklist Lookups

An example of blacklist results.

An example of blacklist results.

Blacklist lookups check our extensive list of blacklists (up to 100 for paid subscribers) and operate in two modes: IP address or Domain blacklists.  This is one of those where checking blacklists for IP addresses produces different results than using a domain.  Read more below.

About Blacklists

For email senders, Blacklists might seem to be a nuisance.  Who are they to prevent you from emailing your customers?  Well, they are legitimately used by nearly every email provider on the internet to reduce spam.  Blacklists setup honeypots that receive spam and use this spam in their algorithms to block illegitimate email.  In fact, Blacklists reduce the amount of email your servers process by as much as 90%.  Think about that for a second…  Your server would need to be 10x more powerful to process all the email you receive without using the email filter capability a blacklist provides.  Blacklists benefit everyone (except the spammers) by reducing the overhead of emailing.

Occasionally, legitimate emailers get caught in a honeypot and added to a blacklists.  That’s how MxToolbox, helping legitimate businesses understand the blacklists they are on and how to get off the list.

IP Blacklists

IP Address blacklists should be checked using the IP address of your mail servers or, in some cases, your web servers.  An IP address on a blacklist indicates that spam or malware has originated from that IP address, or potentially there is an email configuration that promotes spamming or is the source of a botnet attack.  Each blacklist specializes in monitoring different types of bad online behavior (spam, malware, botnets, exploitable email configurations, etc), so check the individual blacklist description for more information.

Domain Blacklists

Domain blacklists are a little different.  A domain blacklist lists domains that have been included in links or content of spam emails or those known to house malicious or exploitative software.  If your domain is on a domain blacklist, chances are your reputation or your website is being used for nefarious purposes and you need to correct it immediately.

Blacklist Detail

If you are blacklisted, MxToolbox is often able to provide information around the blacklist you are on.  This may include your reason for listing.  You will find a DETAIL button for each blacklist upon which you are listed.  For example, CBL is primarily for sending spam, probably resulting from a malware or virus attack.  Now you know what to check your server for before approaching the blacklist for delisting!

Delisting Information

An example of delisting information available on

An example of delisting information available on

You’re on a blacklist and you want off.  On each blacklist detail page, MxToolbox provides links and steps for delisting your mail servers from the blacklist.  Each blacklist is a little different.  Some may require more information, others may just require you to fill out a request form.  Regardless, you must fix the problem before you request delisting!  If you don’t you will be relisted and most likely have to jump through bigger hoops or experience longer delays the next time you request delisting.

Note:  Some blacklists ask for donations or payments for express delisting.  It is MxToolbox’s belief that delisting should be free.  We only search blacklists that are legitimately used by companies or organizations to reject email and have free delisting.  It is up to you to choose if you would like to pay for an express delisting or donate to the blacklist.  Contact Us is you feel like a blacklist is unfair or unethical.

The next topic is analyzing email server setups and troubleshooting using MxToolbox.

How can I make full use of my MxToolbox account?

MxToolbox has a suite of 30+ tools that makes it easier for IT Professionals and others to do their daily jobs, like setting up and validating email servers, DNS and network configurations or developing and maintaining websites.  With this many tools to choose from, it can be daunting for a new user to get the most out of the site.

This series of posts will give you an idea of the features of MxToolbox and how best to use MxToolbox to go about your daily tasks, including detailed use cases from our experts.  We will add links below as we expand this series.

Today’s topic is Free Accounts

Free Users

First off, most of our tools are free to use. You can use them as much as you’d like and they will still be free.  That’s our culture.  There are a handful of paid tools, mostly for power users in our Professional interface (more about those later).  You can use our free tools whether you decide to register or remain anonymous.  However, registration gives you access to a free monitor, which you might find useful, so we always recommend registering.

Use the Tools

Our tools are concentrated in the following categories to make executing your daily tasks easier.  All of our tools can be accessed from the More Tools page and while our most used tools (described below) can be accessed using the Supertool via a drop-down or command-line style interface.

Running a Lookup

  • Go to the Supertool page
  • Select from drop down the query you would like to run or, optionally, type your query.  For example, you can type “” to run an MX lookup on our domain.

Use the IP address or domain that you are researching.  
Note:  Some queries require either an IP address or domain while a few accept both arguments.  Those with different arguments may have differing results depending on the argument.  Other queries may require a selector.  Check out the help on the lookup page for more information.

Other Parts in this Series

Part 2 – Blacklist Lookups

Part 3 – Email Lookups

Part 4 – DNS Lookups

Part 5 – HTTP/HTTPS or Website Lookups

Part 6 – Domain Health Check

Part 7 – Network Tools

Part 8 – Free Monitors

Part 9 – Paid Subscriptions and Tools

Part 10 – Paid Monitoring

Part 11 – Premium Monitors

Check back to this page as we add new entries around tools and use cases.