.NET Email Validation

$ 99.12


"I was looking for a .NET component that would save me the time and trouble of reading RFC 821 and writing a bunch of complex regexes. Instead, I found the Kellerman .NET Email Validation Library which goes far beyond simple validation and detects so many things that I didn’t even think about: fake emails, disposable addresses, grey listing and much more. Plus, like the other Kellerman libraries, it is very easy to use with just a line or two of code. Highly recommended."

Wayne Hiner

The .NET Email Validation Library by Kellerman Software is the cutting edge of email validation. We spent months analyzing fake email addresses. The fake email pattern checker eliminates numerous bad emails that actually return as valid email addresses with our competitors. It detects mail servers that implement grey listing so the email addresses can be verified later. It detects servers that are blocking your mail server. It detects disposable email addresses such as mailinator.com. It detects free email addresses. Sick of curse words in your mailing list? Eliminate them. The .NET Email Validation library doesn't have levels; it has options. Choose whatever options suit your project. Yes it performs industry standard syntax checking, mxRecord (Mail Exchange Record) lookups, and mailbox verification using multiple threads asynchronously. It supports all .NET project types including .NET Framework .NET Core, Mono, Xamarin iOS, Xamarin Mac, Xamarin Android, UWP, Unity, .NET 5, and .NET 6. It can be used with any .NET language including VB.NET and C#. Download the full list of features.

While it can be purchased separately, this product is also included in the Gold Suite. Gold Suite subscribers receive all product updates and all new products as part of a yearly subscription. It is the best value in the industry.


Feature Description
Industry Standard Checking Supports RFC 821 syntax checking of email addresses, MxRecord (Mail Exchange Record) lookup, and Mailbox account checking via SMTP. It uses multiple threads and takes advantage of multiple and multi-core processors.
Proxy Support Supports 4, 4a, 5, and HTTP Proxies. Also has the ability to set the DNS Server when performing MX Record Lookups
Simple to Use Validate an email, or a list of hundreds of thousands of emails, with a single line of code.
Fake Email Pattern Matcher Did you know abc@abc.com is a valid email address? It has a valid syntax, a valid mail server and the mail server actually returns true for a mailbox check. The fake email pattern matcher recognizes thousands of bogus email addresses just like this example.
Disposable Email Addresses Prevent bots from posting messages on your message board by preventing them from using disposable email addresses. It recognizes thousands of disposable email domains such as mailinator.com, spamavert.com, and spamex.com.
Free Email Addresses One way to prevent fraud is to disallow free email addresses when customers order products on your eCommerce site. The .NET Email Validation Library recognizes thousands of free email domains such as hotmail.com, gmail.com, and rediffmail.com.
Detects Greylisting When grey listing is in place, a mail box check cannot be performed. The .NET Email Validation Library detects grey listing to verify the address at a later time.
Detects Blocking Detect when your mail server or IP Address is being blocked by anti-spam software. This happens in shared hosting environments when a spammer uses the same mail server as your business. It detects blocking by spamhaus, SPF, SORBS, SpamCop, spamblock.outblaze, 86.blacklist.zap, SORBS and many others.
Documentation Industry standard formatted help and an easy to use demo is included.
Royalty Free Distribution Include with any .NET project royalty free.
1 Year Free Upgrades Purchase today and all upgrades are free for the next year.
60 Day Money Back Guarantee At Kellerman Software, we want you to be totally satisfied with your purchase. Receive a refund within 60 days when ordering from KellermanSoftware.com. Source code versions are non-refundable due to their nature.
Lifetime Support Lifetime E-mail technical support is included.

If you have a project need to validate email in .NET, the .NET Email Validation Library has the highest capabilities to validate email in C#.

How does the .NET Email Validation Library stack up against the competition?

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"I was looking for an email verifier to integrate into our app. I needed a solution that was both fast and reliable. After trying a few different ones, I came across Kellerman .NET Email Validation Library and I knew I had found exactly what I was looking for. Very easy to integrate, extremely fast and accurate. I highly recommend it to anybody looking for an email verifier solution."

Sean Mancuso

Download a free 30 day trial today.

  • Full working version
  • Includes technical support
  • Compatible with Windows, macOS, Linux, iOS, Android and Docker.
  • Compatible with .NET Framework 3.5 and higher, .NET Core 2.0 and higher, Mono 5.4 and higher, Xamarin.iOS 10.14 and higher, Xamarin.Mac 3.8 and higher, Xamarin.Android 8.0 and higher, Universal Windows Platform 10.0.16299 and higher, Unity 2018.1 and higher, .NET 5, and .NET 6.

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"With the expansion of the top level domains and the flood of fake email addresses it was crucial that our European customer database was validated not only for the Marketing department campaigns, but also due to all Shipping documents and Invoices being mailed electronically to our customers. As with other Kellerman libraries it took one of our developers just a few hours to integrate the .Net Email validation library into our ERP system. Now we have real-time checking of all new customer email addresses. I can highly recommend using Kellermans libraries, simple to implement, very stable, and they work! "

Graham Dodd, Director of IT
Falk & Ross

When using this software you meet the following system requirements.

  • Compatible with Windows, macOS, Linux, iOS, Android and Docker.
  • Compatible with .NET Framework 3.5 and higher, .NET Core 2.0 and higher, Mono 5.4 and higher, Xamarin.iOS 10.14 and higher, Xamarin.Mac 3.8 and higher, Xamarin.Android 8.0 and higher, Universal Windows Platform 10.0.16299 and higher, Unity 2018.1 and higher, .NET 5, and .NET 6.

Using .NET Email Validation Library is easy. Instantiate the object and call a method. See the example below which detects a typo in the email address.

Result myResult;
EmailValidation valid = new EmailValidation();

myResult = valid.ValidEmail("bob.smith@gmaill.com");

Q: How do I use my license key?
A: EmailValidation valid = new EmailValidation("my user name","my license key");

Q: I lost my license key how do I retrieve it?
A: Go to your account

Q: I lost my software how do I retrieve it?
A: Go to downloads

Q: Where can I download the latest version of my software?
A: Click the download tab.

Q: How does the licensing work?
A: Each developer that uses the .NET Email Validation Library must have a license. You may distribute your application to end users royalty free or use it on an unlimited number of servers. A site license is for all the developers in a single building. An enterprise license would be for numerous developers in multiple buildings.

Q: Does the .NET Email Validation Library work with ASP.NET?
A: Yes, the .NET Email Validation Library works with any .NET project type.

Q: What happens when the trial expires?
A: An exception is thrown, indicating that the trial is expired.

Q: I am getting a message saying that Port 25 is Blocked. How do I get around this?
A: SMTP validation occurs on port 25, that is per the spec of SMTP. A different port cannot be used. Your Internet Service Provider has blocked port 25 because this port is also used to send spam. To get around this you can purchase an air card or wifi hotspot or run the email validation on your email server.

Q: If we integrate your library in our applications, will it connect your server to validate email?
A: No, it contacts each email mail server directly. For example, if it is john@hotmail.com address it will contact hotmail.com to figure out if the address is valid.

Q: If you have list of fake email domains/disposed email domains, how often do you upgrade the list ? How we can get upgrades?
A: We have many customers that use the .NET Email Validation Library. As soon as a customer notifies us of a fake domain or disposed email domain it goes into a hotfix. Normally it is released a within a week after that. When you purchase the .NET Email Validation Library updates are free for a year.

Q: Will this library use our smtp server for validating emails?
A: No, it contacts each email mail server directly. For example, if it is john@hotmail.com address it will contact hotmail.com to figure out if the address is valid.

Q: How does this library works?
A: The .NET Email Validation creates up to 50 threads to perform validation. Queued emails are picked up by available threads. The requested validation options are performed for each email address until one of the validations fail.

Q: Will this library send any spam emails to validate email addresses?
A: No, it contacts individual SMTP Mail Servers and asks if an email address is valid. However, if your IP Address does not normally communicate with other SMTP Servers, you will have to warm up your IP Address or the remote SMTP server may think you are going to send spam.

Q: Do you charge per email validation?
A: No, an unlimited number of emails can be validated with the purchased version.

Q: We are receiving messages like: Maximum number of emails validated for trial. No validation performed. Can we test the full version?
A: The trial version has a limit on the amount of email addresses that can be validated at one time. Please purchase to test the full version.

Q: How much do you charge to get source code in c#?
A: See the Developer Licenses drop down.

Q: How often we need to upgrade your library?
A: After purchasing, major and minor updates are free for a year. After that, upgrades are 50% off the retail cost.

Q: Is the license perpetual?
A: Yes.

Q: What are the best practices for using your library?
1. The best option is to run the .NET Email Validation Library on your mail server. No SPF record is required and reverse IP lookups required by other mail servers will succeed.
2. The second best option is to run the .NET Email Validation Library on a web server with an SPF record. When validating emails some validations will fail because of reverse IP lookups.
3. The third option is to run the .NET Email Validation Library on a web server without an SPF record. Most likely the server will be blocked if performing more than 10,000 validations per day.
4. The fourth option is to run on a PC with port 25 open. Most likely the IP Address of your PC will be blocked if performing more than 10,000 validations per day.
5. The worst option is to run on a PC with port 25 blocked. Only simply regex validation can be performed.

If you normally don’t send out that many emails from your IP address, it may need to be warmed up.

If you are planning to verify more than about 10,000 email addresses at a time, it is important to ramp up your email verification in order to build the reputation of your IP address. The problem is if you were to verify a large number of email addresses when your IP address does not normally send out that many emails, the ISPs are much more likely to defer or block your verification. Once you have ramped up successfully, you can verify a much higher email addresses.

Recommended Schedule (verifications can be broken up into smaller batches sent every 4 to 6 hours):
• Verify 10,000 email addresses on days 1, 2 and 3
• Verify 20,000 email addresses on days 4, 5 & 6
• Verify 40,000 email addresses on days 7, 8 & 9
• Verify 80,000 email addresses on days 10, 11 & 12
• Verify 160,000 email addresses on days 13, 14 & 15
• Verify 300,000 email addresses on days 16 +

Date Version Description
11/8/2008 1.0 Kellerman Software proudly announces the availability of the .NET Email Validation Library. Verify the syntax, mail server, and mailbox of email addresses. Also detects curse words, verifies the TLD (Top Level Domain), detects disposable emails, and detects free emails. The only email verification software on the market that detects grey listing and blocking.
12/20/2008 1.05 This update includes major enhancements to the help file including expanded C# and VB.NET examples.
4/25/2009 1.07 This update includes fixes for the BestConnectOptions and a licensing issue.
3/10/2010 1.14 This is a critical update that fixes an out of memory issue when validating more than 240,000 email addresses asynchronously.
7/9/2010 1.17 This release includes a .NET Framework 4.0 build compatible with Visual Studio 2010.
12/31/2010 1.18 By several customer requests, this is a change in the obfuscation of all assemblies which will now show the true stack trace if an exception occurs.
5/4/2011 1.19 This release fixes a ThreadPool configuration issue when running on IIS6.
6/27/2011 1.20 This fixes a trial mode issue for the .NET 4.0 framework in a medium trust environment.
7/21/2011 1.21 This fixes an issue when connecting on an invalid port (port 80) to a hotmail mail exchange server. It now will return with the standard SmtpConnect exception when an invalid port is specified.
8/17/2012 1.24 The top level domain validation has been updated with the latest country and three letter codes.
10/1/2012 1.31 Primary MX Record detection has been improved. Several small defects were also corrected.
10/23/2012 1.34 Improvements have been made for the initial connection detection.
11/5/2012 1.36 Additional grey listing detection has been added.
12/21/2012 1.37 Additional grey listing detection has been added. Added licensing help in the demo source and also in the getting started section of the help file.
2/19/2013 1.41 Additional grey listing detection and disposable email servers has been added.
3/23/2013 1.42 By customer request, it now handles invalid MX Records. When the IP Address of the MX Record is null, it will now take the A Record.
5/1/2013 2.00 New features include, proxy support, ability to set the DNS Server when performing MX Record Lookups, ability to set the from IP Address when performing SMTP Connections, ability to register the demo without re-compiling, ability to import a list of emails into the demo, ability to asynchronously add a list while processing is occuring, option to ignore connectivity errors, additional grey listing support, and additional black listing support.
5/18/2013 2.04 This releases fixes an issue with the SMTP response handling of some servers. It also fixes an issue with the fake email pattern checker.
6/1/2013 2.05 The FromIpAddress functionality requested by a customer has been taken out because it violates the RFC for SMTP communication.
9/9/2013 2.05 This release fixes an issue for Socks 5 proxy in some environments. It also includes a new feature to define the LocalEndPoint.
11/29/2013 2.07 New build for .NET Framework 4.5 and 4.5.1.
10/19/2014 2.08 This update fixes a compatibility issue with projects using ClickOnce deployments.
1/7/2015 2.12 This update includes a refresh of the top level domains and a bug fix where q.com should be valid.
4/29/2015 2.15 Change blocking to be less restrictive. Ability to detect fake IP address responses. Fix for defect where the first character is white space or the last character is white space. FromEmail and FromMailServer are now required due to internet service providers tightening restrictions.
2/24/2016 2.20 Builds for .NET Framework 4.5.2 and 4.6. The library remains 100% managed code but is now compatible with COM.
10/22/2016 2.23 Fix for Cryptography Error with FIPS compliant mode.
2/28/2017 2.26 Support for Unicode email addresses and domains. Refresh of all new Top Level Domains from ICAN. Large performance improvement for Basic Syntax Checking.
6/11/2017 2.27 Refresh of top level domains.
8/14/2017 3.0 Major release. Now compatible with .NET Core 1.1 and higher.
11/13/2017 3.03 Bug fix when validating a list of addresses in .NET Core. Fix for htmail.com
8/31/2018 3.12 Top level domains were updated from ICANN. Fix for basic syntax logic to allow semicolons inside of quoted email addresses.
9/14/2019 3.13 Builds for .NET Framework 4.7, 4.7.1, 4.7.2, and 4.8.
4/4/2020 3.15 Added guerrillamail, sharklasers, and spam4.me disposable domains.
8/9/2020 4.00 New features: catch all testing and ability to specify user messages. Thousands of disposable and free email domains have been added. Now compatible with .NET Standard 2.0, Mono 5.4, Xamarin.IOS 10.14, Xamarin.Mac 3.8, Xamarin.Android 8.0, UWP 10.0.16299 or Unity 2018.1.
2/10/2021 4.12 Fix for BeginInvoke Platform Not Supported with .NET Core for ValidateList and ValidateListAsync.
2/23/2021 4.14 Support for aliased email sub addressing like john.smith+1234@gmail.com. Added new Top Level Domains.
7/28/2022 4.17 Fix Object Reference Error for Xamarin Forms.
12/17/2022 4.18 Fix for ValidateList for .NET Standard.