Just updated to El capitan, now I cannot send emails from each of the different accounts I have, I can only do it select one favorite server which is absurd ?

My Mail, since the upgrade, has gone mad. I can't send via my own website account.

Also email addresses I used to have - and deleted more than a year ago - showed in Mail when I opened it.

I have noticed other people have similar issues since the upgrade and have posted separately.

I'm having this same issue. I have multiple email accounts enabled (Exchange and Gmail), yet there's no option to switch accounts in a new compose window. See attached screenshot. So I can only send emails from the default account, which I agree, is absurd. This has gotta be a bug (so I filed a report: Radar #22935487).

SSame is happening to me - I deleted and re-added accounts which worked for some accounts , yahoo, gmail and outlook, but still having issues with iCloud email account - it refuses to verify the accounts. But re-adding seems to resolve - not good !!!!

just got off support chat with apple ! deleted and re-added accounts solved problem. For iCloud account i had to sign out of iCloud account and then go back in and then it was all sorted.

obviously upgrade messed up settings on mail, simply re-adding accounts sorted it - bit rubbish, but was easy to fix - if a bit of a pain

I had to add my work Exchange to my Mail App because Outlook 2011 doesn't work with EL Capitan. Thanks!!!

Problem I am having is that I have Mac Mail set to send via the mailbox that is selected and it will work for iCloud and Gmail accounts but not exchange. What went wrong there Apple?

simple reboot helps to fix this

I had this problem for all my POP accounts (Comcast for me). Specifically, mail was requesting a password to permit outgoing mail, but not recognizing the correct passwords when typed in at the prompt. I accessed the "Preferences" menu from the Mail program then Account information and then clicked on the "outgoing mail server (SMTP)" and clicked on the "edit SMPT server list" that appeared at the bottom of the drop down menu and found that the password box was empty. Once I input the correct passwords in this location I was able to receive mail again.

Furious. I have no clue how to re-set up accounts! What am I supposed to do now?!! C'mon Apple. This is why I left PCs!

Indeed, a reboot helped here as well.

It is a pain but, not hard to resolve.

Go to settings and find internet accounts

delete the existing account - use the minus sign

then re-add the account using the plus sign

It's usually simple to add an account e.g gmail account - simply enter email address and password and it should auto find the rest

if struggling you can always contact Apple online support people who can talk you through the process

Good luck

As many of you, I am having the same problem with 'Mail'.

It just TOTALLY ****** me off that every 'upgrade' is a downgrade and randomly screws up functions that take me hours to repair.

Looks like the developers are smoking the wrong stuff.

Come on, Apple !!! This is CRAZY. Get your act back together!

Since my posting on this subject it has started to work. I'm sure there was a reboot in there somewhere and that is likely what fixed it.

The issue was with he Exchange account as the reply to account when it was selected. I will be going to Office 2016 this week and at least it works better with El Capitan than Office 2011 which was why I had to use Mac Mail for Exchange in the first place.

Microsoft may have screwed the pooch on this one but Apple isn't completely innocent.

I searched on-line and found this simple solution that worked for me:

http://jimmymacsupport.com/os-x-el-capitan-fix-cant-send-email-after-upgrade/

For what it's worth, I googled "El Capitan can't send email" and that link was the third hit. Apple Support can sometimes be information overload when all you want is a quick fix. Hope this helps.

I tried this and THANK YOU, it worked!!! When I called Apple Support I got a different answer from each person I spoke with. However, I'm synching Google now so will see if it holds. Fingers crossed xx

I was having issues connecting to godaddy accounts with El Capitan's iMail. I found first delete all accounts associated with that server then add them again is the solution.