Why does Apple Mail preview pane display only sender's first name?

Question

Some, but not all, of the mail I receive shows only the sender's first name in the preview pane. I've checked the three areas others have mentioned as possible sources of the problem: 1.) Both first and last names appear for these senders in my Contacts. 2.) None of these senders appear with only first names in my Previous Recipients list. 3.) The full headers don't show first name only.
When I used Entourage, emails from the same senders never showed only first names in the preview pane.
Is this a bug in Apple Mail? Is there a workaround?

Answer 1

I came here looking for a similar answer. Some of my HTML messages show up just fine in Mail 3.5. Others, I get the plane text alternative or a bunch of raw HTML. With no answer in sight on the Discussion groups, I decided to look at the raw mail message of one of the offending emails.
Under the View menu I found a sub menu called Message then there are 6 choices beneath that:
*Long Headers*
*Raw Source* (which is what I was looking for)
+(and then below a separator I found a surprise!)+
*Plain Text Alternative* (grayed out)
*Previous Alternative* (grayed out)
*Next Alternative* (available)
*Best Alternative* (available)
Only the appropriate ones for the current message display format are available.
So low and behold selecting "next" or "best" changed my message into fully readable HTML format with pictures, formatting, etc.
I am assuming that something in the way that the multipart MIME message is assembled by some senders' systems does not sit well with Mail. I'm not going to bother figuring it out, but I'm sure that close examination of the raw message would give some clues.
Now if only I could figure out how to choose the message format based on the sender, I could eliminate having to change every message that comes in from that sender. Maybe AppleScript and a Mail Rule?
Message was edited by: sjmvideo