I can't receive emails in Thunderbird. Settings look correct. Not sure what the problem is.

My internet provider (TWC) said I should contact you about this. I have two email accounts assigned to Thunderbird, but I'm receiving incoming email to just the one account. I can send emails on mine, but can't receive any. The second email account sends & receives just fine. TWC said my incoming is mail.twc.com & the port is110. I see under my settings there is no "Outgoing server (SMTP)" showing under Security settings on the list. The second email account does show this setting. I can access new incoming emails logging on to TWC site, but can't retrieve them opening in Thunderbird. Please advise. Thanks.