Sourced from swiftmailer/swiftmailer's changelog.

5.4.12 (2018-07-31)

• fixed typo

5.4.11 (2018-07-31)

• fixed startTLS support for PHP 5.6-

5.4.10 (2018-07-27)

• fixed startTLS only allowed tls1.0, now allowed: tls1.0, tls1.1, tls1.2

5.4.9 (2018-01-23)

• no changes, last version of the 5.x series

5.4.8 (2017-05-01)

• fixed encoding inheritance in addPart()
• fixed sorting MIME children when their types are equal

5.4.7 (2017-04-20)

• fixed NTLMAuthenticator clobbering bcmath scale

5.4.6 (2017-02-13)

• removed exceptions thrown in destructors as they lead to fatal errors
• switched to use sha256 by default in DKIM as per the RFC
• fixed an 'Undefined variable: pipes' PHP notice
• fixed long To headers when using the mail transport
• fixed NTLMAuthenticator when no domain is passed with the username
• prevented fatal error during unserialization of a message
• fixed a PHP warning when sending a message that has a length of a multiple of 8192

5.4.5 (2016-12-29)

• SECURITY FIX: fixed CVE-2016-10074 by disallowing potentially unsafe shell characters

  Prior to 5.4.5, the mail transport (Swift_Transport_MailTransport) was vulnerable to passing arbitrary shell arguments if the "From", "ReturnPath" or "Sender" header came from a non-trusted source, potentially allowing Remote Code Execution

... (truncated)

• 181b89f prepared the 5.4.12 release
• dccdd7c updated CHANGES
• d96063e fixed typo
• 7c6640e prepared the 5.4.11 release
• 5a82b2e updated CHANGES
• d9aed42 refactored code
• 421299e bug #1112 wxu: Fix release version is not compatible with low version PHP (wxu)
• c14b7af wxu: Fix release version is not compatible with low version PHP
• dd71cc1 prepared the 5.4.10 release
• 5fbe82f Allow explicit tls1.0, tls1.1, tls1.2 for startTLS
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