a.       Server hostname: smtp-mail.outlook.com.
         b.      Port: 587
         c.       SSL: STARTTLS.
         d.      Authentication: Normal password.

Hello, I am at my wit's end trying to figure out why I can't send from my outlook.com e-mail account via Thunderbird. I have at least triple checked my outgoing server settings and password. I have used my password to get in fine to the outlook.com e-mail portal. However, whenever I try to send from my outlook.com e-mail using Thunderbird, the same error keeps popping up: "Login to server smtp-mail.outlook.com failed." Again, I know the password is correct because not only can I get in through outlook.com, but Thunderbird can receive mail fine. I have determined the outgoing outlook.com settings as this: a. Server hostname: smtp-mail.outlook.com. b. Port: 587 c. SSL: STARTTLS. d. Authentication: Normal password. The funny part is that I also use a Hotmail account using Thunderbird as an e-mail client with the same settings, and I can receive and send perfectly with them. Meanwhile, I have the same settings on my outlook.com account and I always get "Login to server smtp-mail.outlook.com failed." I have tried port 25 (instead of 587), "changed" and deleted the password in Thunderbird to make sure the password is correct (it is), and disabled all add-ons to make sure it wasn't them. Nothing works! I have even tried cleaning cache via CCleaner (I heard it worked for someone) and nothing. I'm officially out of options, and I've Googled with problem to death to which no one seems to know how to solve this problem. Any help or ideas would be appreciated. Thanks! Update: I did some testing using another e-mail client (Inky). I get a very interesting error message: Incoming server: Success! Server: imap-mail.outlook.com User: ***@outlook.com Port: 993 Protocol: IMAP Outgoing server: A problem occurred. The server rejected your username and/or password. Please start over and re-enter your e-mail address and password. I just had Inky use the default settings for Outlook settings, and then this happened, which is basically the same thing that happened with Thunderbird (can't login to outgoing server even though e-mail and password is correct). Here's the kicker: when I use Windows Mail (the app that comes with Windows 10, I can send/receive fine). All I had to do was add my e-mail (the Mail app configured the account behind the scenes), and done. Can anyone give me any ideas to why my outlook.com account can't send, but my hotmail.com works perfectly on Thunderbird, even though they share the same exact e-mail settings?