Q: Mail not working with El Capitan

I had the same problem where as I installed El Capitan and Mail would not work for the many web base email addresses I have. The problem was intermittent, and would occur differently from hour to hour, day to day.  The way I corrected the issue after hours on the phone with Apple Tech was to erase all of the email accounts, everyone, not just a couple star with a blank slate. And as you re create the new accounts for your email addresses you will find that they should now work.  Warning: put all your emails in mailbox folders off the server before erasing otherwise those emails could be lost.  Believe me after being on the phone for an hour and a half, it was as simple as the erasing of the old accounts and starting fresh that solved my issue, no thanks to apple support.

Spoke too soon the incoming servers are not working again.

See my last - try 1) shutting down Mail.app, 2) Turn off wi-fi , turn it back on again, reboot. 

....does it work again for you? 

Same issue - my small business is suffering because or El CRAPitan. Email works for about ten minutes, then no longer able to receive mail.  NOTHING works...so we reboot, are good far a while, then reboot.  Starting to think I should be able to charge Apple for the incredible loss of productivity. I simply can't believe they could put out an update that is so staggeringly bad, particularly with email...one of the most common uses for any home or office computer.

Tell anyone you know NOT TO UPDATE! Apple....where the heck is a fix?

Not acceptable - seriously and criminally. We pay top dollar and expect first-class product and service, instead we're now expected to act as unpaid beta testers.

Steve would not have approved of and released such a shambolic system. I (and obviously a multitude of other professionals who require their mail to flow without issues) are paying dearly for, and subsidising Tim's incompetence. It's time to fire the CEO and bill him for the time and business lost due to his slackness. And spare us the weak excuses!

Yours disaffectedly.

Thank you all so much for your comments and help. I WILL NOT UPDATE to El Capitan until Apple gets this fixed!!!!

I wonder if  beta 10.11.2 fixes that problem..

To try would mean a lot of computer downtime, l am not the one testing.

l will monitor this right here.

Thanks for the info. On my system, the option to uncheck "automatically detect .." is greyed out, and checked. I can't figure out how to liberate it so I can uncheck it.  Any hints?

On a MacBook Pro, is it possible to use a mail program that is not Apple Mail?

I would like to do that because after upgrading to El Capitan, I cannot search in Apple Mail any more. I can't live with that, nor do I really have time to search hundreds of pages for a possible solution to the problem, so I think the easiest thing to do for me would be to switch to using a non-Apple mail program. Does anybody have any recommendations?

Thanks!

Unreal that they released this insanely buggy OS. I've been on El Capitain for a week or so and it is downright terrible. The mail app is now useless until they release a fix version of this OS. I can only receive email, not send it. The mail app seems to be corrupting passwords-all I get are errors and prompts asking for my password like others have noted as well. I've tried every fix I can find and nothing works.

If I can find an alternative mail program at this point, I will jump on it. Good luck everyone. I hope they fix this soon.

I am still no nearer working out what is going wrong with Mail in El Capitan.

It seems that my outgoing server password is "forgotten" by mail on a random basis. This morning when I logged on it was still in place and I could send and receive emails. Only an hour or so later when I opened Mail again it had disappeared. So far today I have had to re-input the password twice. Yesterday it was three or four times. I can detect no pattern which might explain this aberrational behaviour.

At least I can get a limited service by repeated input of my password so I am not as badly off as others on this thread but, come on Apple, SORT IT OUT!

I was able to get my Earthlink account working by going to using the Edit SMTP Server List under Outgoing Mail Server drop down in Mail Preferences. There was no password in the Advanced tab. It worked after entering the password as seen below. Please note I concurrently tried unchecking Automatically detect and maintain account setting, toggled the Enable This Account and other voodoo.

Thanks for that info. I checked my settings and the server ports were not set to what my web host listed for SSL. I edited those and knock on wood, so far so good. My email is working for now.

May be a good idea to check those Server ports both incoming and outgoing. I had to change both.

I tried this approach several times. Each time - the passwords were 'forgotten" - sometimes within minutes, other times only after several hours of uninterrupted good service.

There is something seriously wrong with the Mail app in Capitan and ther sooner Apple realizes this and fixes it - the happier many people will be!