MailBee.NET Security Component

MailBee.NET Security Component

Add S/MIME and extended SSL support to your e-mail applications
MailBee.NET Objects bundle includes SMTP, POP3, IMAP, EWS, Security, Antispam, Outlook Converter, Address Validator, PDF components and also BounceMail, HTML, MIME, ICalVCard components which are a free functionality.

MailBee.NET Security allows components ofMailBee.NET Objects family to communicate with TLS/SSL enabled mail servers and use S/MIME for e-mail encryption. Backed with commercial-grade support.

Basic functionality (ability to connect to TLS/SSL enabled mail servers) is available for all MailBee.NET components at no additional cost.

Advanced functionality (S/MIME and SSL certificates) can be activated using a license key. The license already comes within MailBee.NET Objects suite. In other cases, it should be purchased separately.

Main classes of Security component are Certificate, CertificateStore, Smime, ClientServerCertificates, Impersonation, Powerup.

Visual Studio


MailBee.NET Security can be used in any .NET language including C# and VB.NET. Supported .NET frameworks include .NET 2.0/3.0/3.5/4.0/4.5/4.6/4.7/4.8, both 32-bit and 64-bit.

MailBee.NET also supports .NET Core 1.0/2.0/3.0/3.1, .NET 5.0/.NET 8.0 and newer including ASP.NET Core and Xamarin, UWP (Universal Windows), Azure.

The component fully supports SSL2, SSL3 and TLS 1.0/1.1/1.2 protocols when communicating with secure SMTP, POP3 and IMAP servers (like Gmail or Hotmail). Both dedicated SSL port and STARTTLS over regular port modes are supported.

S/MIME functionality includes signing, checking signatures, e-mail encrypting and decryption, API for accessing and enumerating certificates and certificate stores in Windows registry and files.

DomainKeys/DKIM functionality allows for validating and creating DK/DKIM signatures which are used by most e-mail providers nowadays to check authenticity of e-mail senders. E-mails signed with DK/DKIM signature are not treated as spam.

Top 100 publisher by ComponentSource

Over the years, MailBee.NET Objects has been among bestsellers on ComponentSource, the world's leading online shop of developer tools.

MailBee.NET Security Component fully supports:


  • S/SMTP
  • S/POP3
  • S/IMAP



  • .CER
  • .P7B
  • .PFX
  • Registry

Servers & Services

  • MS Exchange
  • Lotus Notes
  • GroupWise
  • IMail
  • MailEnable
  • AxiGen
  • SmarterMail
  • SurgeMail
  • MDaemon
  • Kerio
  • CommuniGate
  • hMailServer
  • Exim
  • Postfix
  • Sendmail
  • Qmail
  • Courier
  • Dovecot
  • Cyrus
  • Zimbra
  • GMail
  • Hotmail
  • Yahoo

...and any SSL-enabled SMTP/POP3/IMAP servers

SMIME Object

  • Encrypt or decrypt e-mails
  • Sign e-mails with a digital signature
  • Verify signatures of e-mails

Other Objects

Certificate Object Features

  • Open certificate from file or memory
  • Save certificate to file
  • Validate certificate

CertificateStore Object Features

  • Open existing or create new certificate store
  • Save certificate store to file
  • Enumerate and find certificates in a store
  • Add or remove certificates in a store

ClientServerCertificates Object Features

  • Assign the client certificate for TLS/SSL connections
  • Examine and validate server certificate

DomainKeys Object Features

  • Sign e-mail with DomainKeys and/or DKIM signature
  • Verify DomainKeys and/or DKIM signature of e-mail (using SMTP component)

Impersonation Object Features

  • Impersonate another user

Powerup Object Features

  • Unlock advanced features of Security component

What's new

Version 12.4

  • .NET 8.0 officially supported

See Version History for details

Version 12.3.1

  • Improved conversion of signed/encrypted messages from EML to Outlook MSG.
  • SHA265RSA support in S/MIME.

Version 12.3

  • TLS 1.3 support.

Version 12.2

  • S/MIME verification of attached signatures improved.

Version 12.1

  • A set of S/MIME methods for encryption/decryption, signature verification, working with certificates in Windows-independent way (can be used in UWP and other non-Win32 environments).
  • Separate UWP .NET Standard 2.0 edition for UWP apps targeting Windows 10 Fall Creators Update and newer. Has no Win32 dependencies and can be used in UWP Release builds published in Microsoft Store.
  • Improved support of S/MIME signed/encrypted e-mails converted from Outlook .MSG files with Outlook Converter component.

Version 12.0

  • .NET Core 2.0 / .NET Standard 2.0 edition revised and improved, including better support of .NET Core 2.1 and 2.2.
  • .NET Standard 2.0 support in UWP. UWP apps targeting Windows 10 Fall Creators Update and newer can use the fully-functional .NET Standard 2.0 edition of MailBee.NET Objects.
  • Improved support of TLS 1.2, now it's selected automatically if supported by the server.
  • The ability to automatically DKIM sign each outgoing mail message (MailMessage.SetDomainKeysSignOnSend property).
  • Empty headers are now added to the message being sent in case if they are DKIM signed.
  • S/MIME signatures are now time-stamped by default. Smime.TimestampOnSign property lets you turn this off (as it's a time-consuming network operation).
  • S/MIME signatures now include full certificate chain, can be turned off with Smime.IncludeWholeChainOnSign property.

Clients Say:

"I've been looking at the MailBee.NET application and love it." Matt Yeager
"Thanks again for your help. I like your products..." Ron Hill
"By the way I love your software. Great work thank you." Dennis Drogemuller