Hotmail alias not working with craigslist messaging system

I have a Hotmail address (which MS converted to Outlook account, but I still sign-in with Hotmail address). I use IE and Win 7. I notice that craigslist messaging system (masking the actual email addresses) does not work correctly with Hotmail aliases. I used an alias as my craigslist account email address, but the craigslist messages went into my primary address in-box and showed addressed to my primary address instead of my alias and my Hotmail/Outlook folder designated for the alias that I used with my craigslist account. But the Amazon.com messaging system (also masking the actual email addresses) works correctly with Hotmail aliases. Also, when I send an email reply to someone else on craigslist, I'm not sure if they see my actual email address or the masked address of the craigslist messaging system. (I don't think there are any real techs at craigslist to answer such questions, so I thought someone on the MS forum might have some insight about this issue.) This isn't a major concern. I doubt that I'll use craigslist much. It looks sort of primitive and feels clunky to use.