以下是一个使用AppleScript在OSX邮件中将某些单词加粗的示例代码：

tell application "Mail"
    set selectedMessages to selection
    repeat with theMessage in selectedMessages
        set messageContent to content of theMessage
        set paragraphsList to paragraphs of messageContent
        
        repeat with theParagraph in paragraphsList
            set paragraphText to text of theParagraph
            set firstThreeCharacters to text 1 thru 3 of paragraphText
            
            if firstThreeCharacters is a number then
                set boldWords to {}
                set wordsList to words of theParagraph
                
                repeat with theWord in wordsList
                    if theWord is "example" or theWord is "words" then
                        set end of boldWords to "" & theWord & ""
                    else
                        set end of boldWords to theWord
                    end if
                end repeat
                
                set newParagraphText to boldWords as string
                set text of theParagraph to newParagraphText
            end if
        end repeat
    end repeat
end tell

此示例代码会将选定的邮件消息中以三位数开头的段落中的"example"和"words"这两个单词加粗。你可以根据需要修改这两个单词，或添加其他需要加粗的单词。

请注意，此代码只会修改选定的邮件消息中的段落文本。如果你想要在所有邮件中运行此代码，请将set selectedMessages to selection改为set selectedMessages to every message of inbox。