Hello,
the E-Mail Designer shows me the following Alert:

This mean in english:
The design that appears to your recipients may not look like this preview, depending on the email service and device. Use the email client preview to ensure that your email appears this way in all inboxes.
Automatic HTML code customization is disabled. Emails designed or updated in Email Designer may not display correctly on all email clients.
What does that mean for my E-Mail Design?
Is there something i can do to fix this?
Thanks