Visualforce HTML Email Template - Ability to Edit Text in Preview Before Sending
I've found a workaround! After checking out the html in firebug, I discovered that the embedded iFrame used contenteditable="false" on the body tag. This was causing the content within the Visualforce email template to be "locked". To circumvent this, I added contenteditable="true" on the outermost table within the email template.
Testing looks good so far - it's working on the regular "Send an Email" page and within the publisher "Answer Customer" tab in the Service Cloud Console. Chrome and Firefox have the same behavior. One oddity - within the publisher, the backspace key doesn't work (delete and highlighting are functional though). I'll update this answer if I learn more!
You can use custom labels like {!$Label.Welcome_back} in non-Visualforce template just fine, they'll work.
Don't let the fact they're not selectable in the template wizard prevent you from trying ;) A lot of the hidden gems are missing in this dumbified (erm... "end user friendly") editor. You can use most of the functions from formulas reference:
Geachte {!BLANKVALUE(Contact.Name, 'Heer of Mevrouw')},
Bedankt voor uw vraag.
{!$Label.Blah_blah}
{!$Label.Kind_regards}
{!User.Name}
...at least as long as nobody decides it's a good idea to edit it in Word and then paste back to the editor in which case there will be loads of hidden <span> etc. and the {!<span>$Label.msg</span>} won't get merged server-side (surprise, surprise).
It seems that HTML editor doesn't like Visualforce and HTML email templates. But I was able to get it to work with "HTML (using letterhead)". Go give it a go - letterheads aren't great but might be close enough to what you need. And they'll be editable by mortals = less tickets to IT support.
This attribute contentEditable="true" is only an HTML attribute, so it enables you to edit the content of what is on an HTML page, but SalesForce doesn't know about your edits or send your changes out with the email.
Editable emails would really be nice, but VF e-mail templates don't seem to have that feature.