Version 1.3 - 2018/11/27
- Reverted curl optimization


Version 1.2 - 2018/07/19
- Ability to remove email from suppression list.
- 5.* compatibility fixes
- Custom callback URL
- Documentation updates

Version 1.1 - 2016/05/14
- Send through a backup mailer if Sparkpost fails
  reasons for failure include unverified sender domain, sending quota exceeded, etc.
  options for a backup mailer are all available in standard CiviCRM (SMTP, sendmail, PHP)
- Support for sending via an IP pool (ie. dedicated IP address at SparkPost)
- Better handling of bounces and interpretation of Sparkpost return codes
- API key is now encrypted in database (cannot be considered secure however)
- 4.7 compatibility fixes (specifically with respect to the settings API)
- Flag emails as transactional for Sparkpost if they are not from CiviMail
- Changed log file location to ConfigAndLog directory
- More precise error messages
- Documentation updates

Version 1.0 - 2016/04/07
- Initial release