Separated debug logging and logger setting methods to include SMTP client parameter for better encapsulation. Removed commented-out code for cleaner and more manageable codebase.
Refactor `DialWithContext` to delegate client creation to `SMTPClientFromDialWithContext`. Add new methods `SendWithSMTPClient`, `CloseWithSMTPClient`, and `ResetWithSMTPClient` to handle specific actions on `smtp.Client`. Simplify `auth`, `sendSingleMsg`, and `tls` methods by passing client as parameters.
Mutex locks are added to ensure thread safety when setting DSN mail return and recipient notify options. This prevents data races in concurrent environments, improving the client's robustness.
Updated tests to correctly assert the absence of an SMTP client on failure. Added concurrent sending tests for DialAndSendWithContext to improve test coverage and reliability. Also, refined the `AutoDiscover` and other client methods to ensure proper parameter use.
Updated the timeout for the DialAndSend context in 'client_test.go' from 5 seconds to 1 minute to ensure sufficient time for the operation to complete. This change helps prevent premature timeouts that can cause test failures.
Introduced a sendMutex to synchronize access to shared resources in the DialAndSendWithContext method. This ensures thread safety when sending multiple messages concurrently. Added a corresponding test to verify the concurrent sending functionality.
Updated the .golangci.toml config to exclude gosec rule G402 in quicksend_test.go. This exclusion is intentional as these tests do not require TLS settings.
Introduced a new io.Writer field `EchoBuffer` and its associated `BufferMutex` to `serverProps`. Updated relevant test code to write SMTP transaction data to `EchoBuffer` if it is set, ensuring thread safety with `BufferMutex`.
Introduce the QuickSend function for sending emails quickly with TLS and optional SMTP authentication. Added comprehensive unit tests to ensure QuickSend works correctly with different authentication mechanisms and handles various error scenarios.
Introduce new methods AttachFromIOFS and EmbedFromIOFS to handle attachments and embeds from a general file system (fs.FS). Updated tests to cover these new functionalities and modified error messages for consistency. Updated README to reflect support for fs.FS.
Updated functions to use the io/fs package instead of embed.FS, making the code more flexible with respect to different filesystem implementations. Revised the method signatures and related documentation to reflect this change.
Extended the `UnmarshalString` function in `auth.go` to recognize "auto", "autodiscover", and "autodiscovery" as `SMTPAuthAutoDiscover`. Corresponding test cases were also added to `auth_test.go` to ensure proper functionality.
Refactor the `preferList` definition in `client.go` for improved readability and consistency. This change ensures the code aligns with standard formatting practices.
Refactor the auth type initialization to prevent incorrect assignments and handle empty supported lists. Added comprehensive test cases to verify auto-discovery selection of the strongest authentication method and ensure robustness against empty or invalid input.
Implemented a mechanism to automatically discover and select the strongest supported SMTP authentication type. This feature simplifies the authentication process for users and enhances security by prioritizing stronger mechanisms based on server capabilities. Corresponding tests and documentation have been updated.
Added gosec to the list of enabled linters in `.golangci.toml`. Defined specific exclusion rules to ignore certain false positives and context-specific issues flagged by gosec, ensuring the linter does not impose on intentional code practices.
Changed the SMTP test server base port and updated the corresponding environment variable name to `TEST_BASEPORT_SMTP`. This ensures consistency across the test setup and CI workflow configuration.
In the CI configuration file, the TEST_BASEPORT environment variable was added to various job scopes. This ensures consistency and allows the test base port to be set properly across different OS versions and Go versions.
Moved TestServerPortBase initialization to use an environment variable `TEST_BASEPORT` if provided. This adjustment helps in specifying custom base ports for running tests, ensuring better flexibility in different testing environments.
Structured the initialization of SendError on connection errors to improve code readability and maintainability. This change affects the error handling in both client_120.go and client_119.go by spreading the error details across multiple lines.
Added support for Enhanced Status Codes (ESC) when checking the SMTP client's extensions. The SendError struct now includes the error code and enhanced status code for improved diagnostics.
Previously, only the isTemp flag was considered when aggregating errors. Now, the error code and enhanced status code from the last error are also included. This ensures more comprehensive error reporting and handling.
Added a check for the ENHANCEDSTATUSCODES extension and included error code and enhanced status code information in SendError. This helps in providing more detailed error reporting and troubleshooting.
Renamed `getErrorCode` function to `errorCode` for consistency. Added new tests for the `enhancedStatusCode` function to validate its behavior with various error scenarios.
