After installing the new Yosemite OS on my iMac I can no longer send email. I can receive email, but not send. I use gmail and can send email on the gmail (google) site, but not on "mail" on my iMac. Any others with this problem? What should we do?

Question

After installing the new Yosemite OS on my iMac I can no longer send email. I can receive email, but not send. I use gmail and can send email on the gmail (google) site, but not on "mail" on my iMac. Any others with this problem? What should we do?

Answer 1

My gmail, which is correctly configured for Mail with gmail SMTP and Google IMAP, works for awhile on Mail, which I leave open while working on other applications. But several times a day I get msg from Google: "We recently blocked a sign-in attempt to your Google Account" . . . and requiring me to verify my account details, re-enter passwords, confirm security settings (or change them from "disable" to "enable less secure methods" and so on). In Mail I also have tried "taking all accounts online", and re-entering my gmail password inside Mail account settings. These steps successfully re-set comms between gmail and Mail ... for awhile, then it happens again. Enough occurrences over a work day that I just quit Mail and revert to accessing gmail directly. Apple Care advisor and an Apple knowledge base article say that Apple can't deal with this, as gmail is third-party app, and they refer me to gmail, and so far I've found nothing helpful there.
From today I also have several instances of a window saying "Mail has unexpectedly closed" and asking me to Re-open it.
I also use Yahoo mail, which stops working with Mac Mail at the same time as gmail, but I do not receive notices to re-verify from Yahoo.
I recently upgraded from Mavericks to Yosemite. The Mail problem happened occasionally with Mavericks but is far more frequent with Yosemite.