Many online tools allow you to back up Yahoo emails. I suggest you use the MacSonik Yahoo backup tool. This program can quickly convert Yahoo mailboxes into multiple file formats like PDF, PST, MBOX, CSV, etc on MacOS. It gives you a mail filter option that allows users to back up or migrate selected emails. Using this tool users can Import their Yahoo Mail emails to multiple email clients such as Office 365, GoDaddy, iCloud, IMAP, Hotmail, Zoho Mail, etc.
