Microsoft Outlook 2010 - not receiving any incoming emails

I manually added a new account and I can send emails just fine, but incoming messages aren't working at all. I tried running the send/receive test and absolutely nothing happens—even when I try sending a test email to myself. A buddy of mine suggested I might need to tweak my inbox settings, but honestly, I have no clue where to start. Does anyone have any ideas?

I'm using AT&T, and I’m certain I configured the POP3 settings correctly, so that shouldn't be the issue. (pop.att.net)

Incoming mail server (POP3): pop.outlook.com
Outgoing mail server (SMTP): smtp.outlook.com

Ah, thank you! It's finally working now.

...I’m actually running into the opposite issue... I can receive emails just fine, but I can't send anything out. 🤔
I went through the steps mentioned above... on my end, it shows AT&T instead of Verizon, and everything seems perfectly fine for receiving messages. But sending is a total dead end.
I've been digging through my settings, thinking maybe there's an option I missed that needs adjusting.

Under the OUTGOING server section, I have the box checked for "My outgoing server (SMTP) requires authentication."

I also have "Use same settings as my incoming mail server" selected. I've tried every single combination, but I keep getting this error message in my inbox that just won't go away... "Client host rejected. Blocked. To send email, please use the smtp.verizon.net server and ensure you are using your full username and password along with SSL/TLS encryption." ...Any ideas on what I should try next? Thanks.