When you say quote: "I have checked the boxes to have messages display in HTML."
So then this means that you've set the arrowed setting as you see in the image below (setting at "
Tools" > "
Options" > "
View Messages" tab > "Default message viewing preference" set to "
HTML"):

- Default Message Viewing Preference setting
What do you mean by quote: "I have to double click to get it to display in HTML"? (double clicking on a message is how an email is opened in the PP inbox list of emails in order to read the email).
In the open message (Menu-bar):
1) When you double/click on an email to open the message then when clicking "
View" in the open message
MENU-BAR you should see in the drop down list that "
HTML" is selected (radio DOT in front of "HTML")?
2) Also under "
Options" > "
HTML options" in the open message
MENU-BAR is "
Block external images and date" UNCHECKED?
If you still having the same issue then in regards to option #1 above: Instead of closing/re-opening the message, try switching to a different view and then back to the original, e.g. assuming it's HTML to start with, switch to plain text and then back to HTML to see if this makes a difference with the problem displaying HTML messages (not intended as a solution but just to see what happens).
Also for PP Pro in regards to messages displayed in FULL HTML: Additional information regarding "Smart HTML Viewing" in the PP Pro application interface main menu: Go to "
Tools" > "
Options" > "
View Messages" and
press F1 to open the
context-sensitive help.
If you're still having problems then try disabling (unchecking) "
Smart HTML viewing" for now (setting at "
Tools" > "
Options" > "
View Messages" tab > upper most option, uncheck the "Smart HTML viewing" option) leaving all other settings as they are and see if this finally helps display messages in HTML (doing this will return to how v3 performed in regards to displaying HTML in messages).