What is meant when Yahoo asks for an alternate email address?
The alternate email address is your real email address outside Yahoo. For example, Yahoo lets me receive mail as donlibes@yahoo.com. However, I told Yahoo that my alternate email address is don@libes.com. I have enabled forwarding so that any mail to donlibes@yahoo.com gets sent to don@libes.com. Note that don@libes.com is actually another alias that sends my email to other places depending upon what the mail is. For example, NIST-related things are sent on to libes@nist.gov. But Yahoo doesn’t know or care about that. No, I have no idea why Yahoo chose the word alternate. It’s not intuitive to me, either.