I want to send out some email and it keeps asking me" who is my email server, like pop3, imap, and http. ?

what are pop3, imap, http

I want to send out some email and it keeps asking me" who is my email server, like pop3, imap, and http. ?
Pop and imap are types of servers for receiving email. SMTP is for sending email. If you use Yahoo's free email, you can only send mail from the mail.yahoo.com web page. If you have an ISP other than Yahoo, ask their customer support for help.

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