Second E-Mail Account (Address)

I have set up a second e-mail account using the same POP3 and SMTP servers (provided by the ISP) as I used to set up the first e-mail account. The first e-mail address is working fine, but when I send an e-mail to the second address (from the default account), it does not appear in the Inbox. The e-mail does appear in the Sent Items folder with no errors.

How do I access the second account to receive/send e-mails?

Thank you for your solution(s).