Thx for the hint, I will check this.
BTW: I think that you're writing about branch develop and TYPO3 8?

Hi Alex,
yes it's TYPO3 8 branch develop.

Did you embed an image via TypoScript? If so, pls write me your configuration.

Here it is:
For all mails the same.
embedImage = COA
embedImage {
10 = IMG_RESOURCE
10 {
wrap = |,
file.import = uploads/pics/
file.import.field = image
file.import.listNum = 0
file.maxW = 120
file.maxH = 120
}

					20 = TEXT
					20.value = fileadmin/templates/img/logo.png
				}

Thx for clearify.
Can you please test the current develop branch? I made some changes and images should be rendered in mails again:

Perfect! It works!
Thanks a lot