Was, is, and will be FREE - even for commercial purposes - and without any adware/spyware/malware.
HCM is probably the smallest so feature-packed e-mail and usenet news reader. It doesn't consume large amounts of RAM and is small enough to fit on a single floppy. Thanks to fast algorithms and highly optimized code (including - but not limited to - MMX and SSE optimizations) application doesn't really have hardware requirements. Carefully designed database format reduces hard drive space requirements and significantly speeds up operations on attachments, on-fly index optimization helps reducing RAM memory usage and folder compression reduces folder sizes even more. Because HCM doesn't use frameworks like GTK+ or wxWidgets, its user interface is snappier and less resource intensive (uses even 9x less memory than most popular open-source e-mail client). It can even use pipelining to download messages with a speed of light.
Works under all Win32-compatible Windows systems, from Windows 95 to Windows 7 (so far).
Fully multithreaded - send and download mail and messages, compose new messages, use finder to look for a lost message. All simultaneously. Without affecting stability.
Fully supports usenet newsgroups (no limits imposed on server or group count). Works as offline and online newsreader (including support for XPAT, Cancel, Supersedes, Cancel-Lock, etc.). Thanks to XOVER support program may filter out/delete blacklisted postings before downloading them (works during message headers retrieval, in both offline and online modes). Also supported are .newsrc files.
Fully supports Unicode - regardless of operating system version - compose and read multilingual mail and news postings, use Unicode in address book, correctly sorts foreign language strings.
Built-in feature-rich, convenient message composer which highlights quotation levels, yet still working blazingly fast even on enormously big messages (four megabytes and above). Also supported is spell checking (if Aspell is installed), text rewrapping, case switching, quotation level walking - among other things. You may even use message templates, macros and fortunes. Supported is a long list of macros.
Supports filtering - filters and sorts incoming and outgoing mail and news postings according to various rules (supported are PCRE regular expressions, operations on header and body and nested rules). May assign points (score) to mail and news messages and automatically detects own messages, placing threads with your messages on top of the stack. Additionally, blacklists allow quick removal of messages sent by disliked/banned senders.
Invulnerable to viruses hidden in messages - does not open automatically any attachments and blocks suspicious files (including those with multiple extensions) while downloading, to not let any dangers slip onto your hard drive. Also detects and defends against suspicious links.
Fully supports Base64, UUE, XXE, yEnc, BtoA, and Quoted-Printable binaries (attachmens). Supports message splitting (split size determined by mail server or user) and combining.
Ultra-fast graphic library supports huge amount of image formats and detects files by their contents, not extension. For instance, JPEG image with a .zip extension will be displayed correctly.
As a one of very few programs, HCM supports folder encryption with powerful yet fast Blowfish algorithm. Contrary to other solutions, HCM doesn't require you to encrypt whole message database and folder decryption may be performed at any time (this should be obvious, but in other software is suported on "recover from backup made before encryption" basis).