Mail cannot log into accounts after El Capitan

On second thought, David L. Gerhardt, you may be better off quitting the Mail app, going to System Preferences > iCloud and unchecking the Mail option for iCloud and then rechecking it. This will basically remove (make inactive) the iCloud email on your Mac and automatically obtain the correct server settings for your account and add the account back to the Mail app.

This may be an easier method, as opposed to entering in the server settings I provided a few moments ago.

Thanks for following those steps! Unfortunately, at this point it's going to be best to contact your email service provider directly and obtain the exact server settings from them directly. They are the only individuals who are able to provide this, and they are necessary to make sure that when your email is being added it's being added with the correct "instructions" (a.k.a. server settings) needed for your Mac to be able to connect with your email provider.

(Included in this article is the information you'll need from them: https://support.apple.com/en-us/HT203995)

Once you have those settings from your email provider, please contact AppleCare and ask them to help you re-add the account as an "Other" account using the exact server settings provided by your email provider, as well as your login and password.

Hope everything works out for you!

Contact AppleCare:

1-800-APL-CARE

Schedule a Call with AppleCare:

getsupport.apple.com

Well... Not what I like, but it worked...

Trying to set up Gmail POP access and kept getting "Unable to verify account name or password"

Went to my Google account and toggled this setting under My Account / Sign-in & security

- Allow less secure apps: ON

Sign in accepted and set up POP access. Works just like before upgrading.

I guess Google considers Apple Mail a "less secure" app.

Do you have two-step verification enabled with your Google account? If so, you'll want to have a look at the below resources as that could be affecting your sign in troubles.

If Mail on your Mac Keeps Asking for Your Mail Password

Sign in Using App Passwords -- Google

I did not have 2 Step on... I'll try turning it on and see what happens...

So yeah, 2 step turned on, used app specific password. Good call Sir.

Perfect! Glad that worked out for you, JJMc32.

Upgraded to El Capitan on my 2012 Mac Pro desk top and lost 'all' my past POP account emails going back to 2010. Not sure how to restore.

Did the rebuild but that only restored todays emails. Also had to reset my password with my company IT person so I could access my account.

Have gone into my Library to locate my Mail V3 file folder but no visible emails there.

It seems that IMAP accounts such as AOL emails were not affected.

Good Question regarding Time Machine as these emails might be stored there but how do you access them?

I hope Apple is tuned in and reading these emails.

Thanks for your advice bren_nan! After a little more research, on my 2 Macs (Mini, and 2015 MacBook Pro), the resolution (thanks to Apple Support) was:

1. Mini had a non-responsive POP acct; turns out the OUTGOING server had a corrupted password. Only on Outgoing. First problem solved.

2. BOTH Macs had a non-responsive iCloud email. The resolution involved quitting Mail, opening Systems Prefs, go to "iCloud", and UNCLICK "Mail". Then LEAVE iCloud (Sys Prefs), go BACK to iCloud, and RECHECK "Mail". NEXT, re-open Mail; go to Prefs; click "iCloud" (i.e., your Apple email acct), and SELECT the "now-visible" iCloud Outgoing Mail Server. (it had DISAPPEARED from BOTH of my Macs). SAVE the Mail Prefs when you exit, and you're home free.

No deleting of accounts, and no saving/restoring messages or accts.

I hope this helps others!

That was exactly the solution! Thanks!

I also had a similar problem with the Mac Mail app unable to connect to Gmail after upgrading to El Capitan.

Upon upgrading I had thousands of old emails flood in. I deleted all, but don't do this as it also wipes them from your iPhone etc!

The Mail app would stay open (I notice other users have reported Mail constantly quits - this did't happen to me) - but Mail would not connect to Gmail and requested I enter my password. Despite entering a correct password, Mail app would display "unable to verify ..."

I tried this solution and all has returned to normal:

Open System Preferences, selected 'Internet Accounts' and delete your Gmail accounts.

Then choose 'Google" from the list on the right hand side of the System Preferences window (it shows iCloud, Exchange, Google, Twitter etc.)

You will be prompted to re-enter your email address and password - then the Mail app resumes working.

Hope this helps!

Guys.. I just managed to sort this. If your gmail is on POP Do the following.

1. Go into System Preferences, Internet Accounts - you will get 2 Gmail Accounts in the left bar. Delete the one for emails (which has and @ icon and not the "g" of gmail).

2. In the other one (with the "g" icon), Disable all services and then Enable mail and messages.

3. Start Apple mail. Your gmail will be up and running.

This will get your gmail up and running in IMAP within the apple mail app. However, POP is not supported anymore I believe. It will download all your mails all over again and you will have to undergo the efforts of deleting the unwanted ones. Unlike POP, they will not remain on your server if you delete this from your computer.

Let me know if it helps.

Cheers!!

Rahul.

This fixed everything for me. Thank you!