Xceed Encryption Library 

The Xceed Encryption library allows you to easily add strong encryption and decryption capability to your Windows applications. Supports the latest industry-standard strong encryption algorithms and offers both symmetrical and public-key cryptography
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cryptlib 

Security toolkit with strong encryption and authentication. Supports many algorithms for symmetric/asymmetric encryption, authentication, and hashing. Free for non-commercial/shareware projects. Written in C. ActiveX and C++ wrappers are available.
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OpenSSL 

Open SSL 0.9.7c lets applications use Secure Sockets Layer (v2/v3), Transport Layer Security (v1), and a general-purpose cryptography library, for data integrity, authenticity, and privacy security features. Perl or Cygwin needed for Win32 compile.
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PBEmail 

If you want to enable your Application for Email Sending, without the need of any configuration at all then PBEmail is right solution for you. PBEmail 2.0 is an ActiveX Control and ActiveX DLL to enable programmers to send Emails from the Application
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CliMail 

CliMail is a set of command line utilities designed to send and receive email. Send plain-text or HTML (with embedded pictures) email with attachments using to, bcc, and cc recipients. List, display or delete email from POP3(S) or IMAP(S) mailboxes
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Winalysis 

Archive Event Logs from multiple computers to a central database. Monitor for changes to files, the registry, users, groups, services, security policies, and more. Restore files and the registry from snapshots. User account auditing and analysis.
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