Q: Outgoing mail server gone under El Capitan

Wow, I have had immense problems with my MacBook air since Yosemite and El Capitan - super slow, virtually a dead machine. The today mail dumped my outbound server details so I came across this thread. Which did not help my mail issue - I had to rebuild all the details again on several accounts. However, after having read the problems I decided to turn ICloud mail settings off and leave them off and my whole computer is working like it did two years ago... flippin annoyed about the problems I have been experiencing... perhaps windows is now a better option.

Yes, this worked. Thanks.

Not very useful, but note this:

I cannot send mail since El Capitan

I log out the mac and logged in as Guest

Then (as Guest) I was able to send the mail .... !!

Suggestion foor Apple: copy the source from the Guest-part of the program and use it in the Account-part of the program

(Probably simple and effectively)

Peter - Please send your suggestion to Apple at http://www.apple.com/feedback/mail.html

Thanks Larry,

I'll do so

I have a verizon pop account that suddenly stopped sending outgoing mail. Most of the suggestions here didn't work or seem relevant to the way I'm set up. The following solution is simple and worked for me (10.11.4 on 2012 mbpro). There are other suggestions on the site I grabbed this from : http://www.computerworld.com/article/2991340/apple-mac/a-quick-guide-to-fixing-e l-capitan-mail-problems.html

Fix Account

This fix seemed to help when OS 10.10.4 shipped earlier this year, so it seems worth trying in OS X El Capitan. If one of your accounts seems to be misbehaving (it may not be sending email, seem inactive or in other ways seem faulty), launch Mail Preferences and select the account in the Accounts tab, then click on the ‘Advanced’ tab.

  • Look at the list and at the top of the list you’ll see the ‘Automatically detect and maintain account settings’ tick box.

  • If it is unchecked, check it and relaunch Mail; if it's checked, then uncheck it, quit and relaunch Mail, reenable it and then quit and relaunch Mail once again.

You should repeat the process for each of your troublesome accounts.

Posted deleted.  Thought I found solution but error came back.

Thanks, this helped me too!  BCV

I was having problems with one of my outgoing email servers showing offline before updating to El Capitan, and did the update hoping that it might fix the problem. Prior to the update, I went round and round with the ISP support people, and seem to have everything entered the correct way. The iCloud solution intrigues me, if I switch to that can I do it for only the account that is having problems? My other one seems to be fine. Will sent mail reflect the email address I wish, or some cloud like thing? The only other thing I can think of is to take the account off of the Mail program, and then put it back on. I'm afraid that if I do that, I will lose my inventory of saved mail. I am sorry to be bothering you with all of this, but I don't seem to be very good at navigating through the communities, and have had no answers to my question. Your discussion seemed pretty much on point. If you can help, or direct me as to how better to inquire, I would much appreciate it.

Thanks!

Had this issue as well.  first try disabling the mail account in control panel "internet accounts", then re-enable it.  If that does not work delete it and add it again.  Should take care of it. 

I am experiencing similar problems to everyone here in that Mail will not send anything (incoming is fine). The server details are correct but it is always showing as offline. There have been no recent changes to my IMAC and I have been running El Capitan with no issues until now! I have tried enabling/disabling the account and  deleting/reinstalling. My machine is up to date with system updates. I do not have an iCloud mail account just one external email account which I have held for several years! I have reviewed all the settings with my ISP as well as following the guidance in this forum but still cannot get the outgoing mail server to show anything other than 'offline'. Any suggestions as to where to go from here? Is Apple aware of this issue, speaking to my ISP (Plusnet UK) they told me that this is a frequent issue with Apple but I haven't seen any acknowledgement of it. My iPhone and iPad use the same account with no issues. I am reluctant to change ISPs having held this email address for more than 10 years!

I've tried the advanced table enable/disable thing...no help. I am at the point of deleting the account and putting it back on, but wondered if you know, whether my accumulated emails will come back. I've way too many of them, I know, but sometimes the old ones come in handy.

If you have a POP account, no, they won't come back, if you have an IMAP account, yes they will. IMAP mirrors what you have on the server. POP moves messages from the server to your machine.

Thanks for the info, I'll save that as a last resort. I've got two non cloud (I don't really want to use the cloud email...I don't need/want another address) POP accounts. One has been working just fine and the other began having problems even before I went to El Capitan. Actually that was my trigger to do the update, because I thought that might fix the problem. Yesterday while I was attempting some of the suggested fixes, the working account's outgoing server just disappeared. I was able to put it back on, and get it working again, but the other still doesn't for outgoing mail. They both work fine on my iPhone. Interestingly, my dad is having the same problem with the same two accounts. I have suggested that he wait to do the El Capitan upgrade until we figure out the problem. I am guessing that at some point, we managed to do the same thing wrong, and that it's just a matter of time until we figure out what it is. If you have any suggestions, please let me know.  Thanks!

Doesn't seem to work if the problem is with a secondary Mail account….