Breaking: #288 - Parameter of Mail Attachment Hook Interface was Changed 

See Issue 288

Description 

Now that the extension has been changed to \TYPO3\CMS\Core\Mail\FluidEmail instead of \TYPO3\CMS\Core\Mail\MailMessage, the attachments have to be handled a bit differently. For this purpose, the first passed parameter and the return parameter have been changed to \TYPO3\CMS\Core\Mail\FluidEmail.

Affected Installations 

Only installations that have registered their own class on the MailAttachmentsHook and thus add their own files to the email are affected.

Migration 

The classes for the first transfer parameter and the return parameter are to be replaced. It may also be necessary to make adjustments to the class if functions were called on the previous \TYPO3\CMS\Core\Mail\MailMessage class that are not available in the \TYPO3\CMS\Core\Mail\FluidEmail class.