This repository implements a Qt-based C++ library for sending emails via SMTP with full MIME support. The library provides asynchronous and synchronous operation modes, TLS/SSL encryption, SMTP authentication (PLAIN and LOGIN), and support for complex email content including plain text, HTML, attachments, and inline files. The architecture follows a modular design separating concerns into distinct components: email address handling, MIME message construction, and SMTP protocol handling. The core components include SmtpClient for managing SMTP connections and protocol state, MimeMessage for constructing email messages with multiple parts, and a hierarchy of MIME part classes (MimeText, MimeHtml, MimeAttachment, etc.) for different content types. The library uses Qt's networking module for socket communication and implements a state machine to handle the SMTP protocol flow. Data flows involve constructing a MIME message with desired content, configuring the SMTP client with server details, establishing connection, authenticating if required, sending the message, and properly closing the connection. The library demonstrates proper encapsulation, error handling, and adherence to SMTP and MIME standards. It depends only on Qt Core and Qt Network modules, making it relatively lightweight for a feature-rich email solution. The implementation includes robust handling of character encodings, MIME formatting, and transfer encoding (Base64 and Quoted-Printable) as required by email standards.