limiting email settings for members

One thing you can do is keep the tinyMCE toolbar in place and remove the buttons you don't want them to be able to use, including the html button so they can not edit the html.  You can also go into the config file for the email toolbar and tell TinyMCE to strip out any tags that are not allowed.  So to make sure they can not post an image, you would remove the image url button.  You can also tell TinyMCE to not allow the image tag <img> so then images can not be inserted.  In Dolphin 7.0.9, you make changes to TinyMCE in BxDolConfig.php.  Look in /inc/classes/ and find BxDolConfig.php.  Open the file in an editor; I use PSPad but you can use any editor that supports file recognition.  I don't know the actually code to add to TinyMCE to block certain tags at this time without looking it up.

To find the particular TinyMCE config that is for the email editor (not sure if it is shared with any other sections) you can match up the toolbars and buttons with what you see in the email editor.  If you don't understand what you are seeing, you can go to the TinyMCE site to learn, http://www.tinymce.com/

Back up the original file by adding an extension of your choice; many use bak, but that could mean a backup copy of any version.  I prefer to mark the original file using .orig and then adding version numbers.  The version numbers help me to track changes.