I had to setup a TYPO3 6.x site with Direct Mail and faced the issue described above. Also images where not displayed in the newsletter, which also seems to be an issue when you use Direct Mail in combination with TYPO3 6.x
To handle those issued the following steps are necessary:
- For your newsletter TS template, do not include "CSS Styled Content", but "CSS Styled Content TYPO3 v4.7". This version of CSS Styled Content still includes the table rendering method.
- Include config.absRefPrefix = {$plugin.tx_directmail_pi1.siteUrl} in your newsletter TS Setup. This fixes the problem with images not being displayed.
After using the settings decribed above, I could successfully send HTML e-mails using Direct Mail in TYPO3 6.x. The solution has been found using TYPO3 forge, where both issues already have been reported.