This seems like a rather basic question, but how do you all deal with salutations that are embedded within the first paragraph of a letter or postcard? 

When the salutation is placed above the text, we use:

            <salute>Dear Freddy</salute>
         <p>How are you?</p>

But we have a postcard that starts like this:

Dear Freddy, how are you

Since salute is not allowed immediately in a paragraph, we could introduce a new element ('opener-inline')  to deal with this:

         <p><opener-inline><salute>Dear Freddy</salute></opener-inline>, how are you?</p>

Or just allow salute within p, which seems the preferable solution to me. 

Similar issues arise in closing salutations, that can also be embedded within regular paragraphs. We have a postscript like this:

             <postscript><p>Mr. Foster came to see me, I am going to
                   him tomorrow. <salute>Good bye. Au revoir!</salute></p></postscript>

where you wouldn't want to move the salute to a fictitious closer.