If you have a defined alias, it will automatically download to your account.

Where do I define the alias. I have an alias and used it today. I see it in my Outlook email but I do not see it in my Thunderbird Hotmail account.

The primary alias must be defined in the online host account. That lets messages go to whatever email client you are using. Are you wanting to SEND from the alias? That's a different question. If that is your intent, you can add it on account page under 'manage identities' which is a button at lower right of that pane.

If Primary Alias means my main Hotmail account then it does download to my Thunderbird account in box but I also want to download emails sent to my Hotmail alias into my main Hotmail in box. Is there some place l need to add the arias to?

I finally see the alias email in my main account inbox. Sorry for taking up your time. I do appreciate the quick response.