Upstream Changelog:

Version 1.4.1:

The auth() method now includes an optional $tls parameter that determines whether or not TLS should be attempted (if supported by the PHP runtime and the remote SMTP server). This parameter defaults to true. (Bug #16349)

Header data can be specified separately from message body data by passing it as the optional second parameter to data(). This is especially useful when an open file resource is being used to supply message data because it allows header fields (like Subject:) to be built dynamically at runtime. (Request #17012)

Version 1.4.0:

The data() method now accepts either a string or a file resource containing the message data. (Request #16962)