SwiftMailer is a flexible, object-oriented PHP library for sending emails via SMTP, Sendmail, or other transports (including third-party APIs). It supports features essential to robust email sending: attachments, HTML vs. plain text bodies, inline images, MIME types, message queues, and signed messages via DKIM. The API lets developers build richly composed messages with multiple parts, headers, and encodings without dealing with raw mail formatting. With built-in retry logic, logging, and error handling, it handles network failures gracefully, integrating into applications or frameworks for background dispatch. Though newer libraries such as Symfony Mailer have emerged, SwiftMailer remains influential in legacy codebases and continues to serve as a reference for well-structured email composition in PHP.
Features
- Multiple transports: SMTP, Sendmail, or custom transport implementations
- Building multipart messages: plain text, HTML, attachments, embedded images etc
- Plugin system (anti-flood, decorators, logging, etc.) for extending behavior in sending or modifying messages
- Support for character set, encoding, setting headers, customizing message metadata
- Good for large attachments; memory usage is optimized for attachments/streams etc.
- Detailed debugging and logging tools; ability to queue or spool messages in certain environments