Trouble with Apple Mail retrieving Yahoo Mail (OS 10.10-Yosemite)

Question

I recently installed Yosemite and Apple/Mac Mail will not work or retrieve my yahoo mail. I can receive my gmail just fine. I've checked all of my settings, used the "mail doctor", taken the account offline and then online again, rebuilt the mailbox and tried to synchronize the account. Nothing seems to work. Oddly enough the program seems to work intermittently (it worked for a few days when I first installed Yosemite then stopped retrieving my yahoo mail and again randomly over this past weekend, but is now back to not pulling any yahoo email). I can read my yahoo emails online just fine, fyi. I would love it if anyone had any suggestions.
PS: I've also downloaded another mail client, called Postbox, which retrieves my yahoo mail just fine, but the program is severely limited and very quirky (search function doesn't work well, difficult to view and arrange your email without it having problems, etc.).

Answer 1

jgallag/Larry:
I, too, have been having this problem with yahoo mail not loading into mac mail.  It has been a persistent problem that I have had to close my mail program and reopen to get emails to come in - this was way before yosemite.  But after upgrading to yosemite, I've had more troubling issues.  I have 2 yahoo mail accounts, a primary account and a special use account.  Right after loading the new upgrade, the special use account was unable to send emails via mac mail.  I could send them from the yahoo server online, and from my iphone, but not from my laptop (mac air).  Two days ago, emails stopped loading into the mac mail program primary yahoo account.  I could send emails, but I could not receive them.  I tried all of the things you also did and suggested, to no avail.  I have found that shutting the system down and rebooting was enough in the past to "wake up" the yahoo account/mac mail account interface, but not this time.  This time, it took moving the laptop to another state and another server to refresh the connection and permit emails to load (I headed out for a business trip today, and emails came in when I reached the hotel).  I did not turn off my computer, just put it in sleep mode during the flight, but apparently a change of scenery is what it wanted.  It would be nice if Larry or someone could either fix this problem or help us navigate through it more efficiently - two days is too long to not load any emails.