Q: Mail SMTP (outgoing) does not work after Yosemite upgrade

And thanks Helicopter Jon for providing the detailed steps for iMansun's fix.

Many of the solutions here did not work for me when I had the same problem, but this one did:

In your settings, uncheck the 2 boxes that say to "automatically detect settings"

Strangely enough, this does NOT always save automatically.  I found that when I unchecked it and closed the box, it asked me to save and then it worked.

Once those boxes stayed unchecked, outgoing mail worked like a charm.

Hope this helps.

Great to hear it worked for you... unfortunately, I haven't been so lucky.  Have tried the editing the mail library option, the unchecking the settings options...etc. all to no avail.

Connection doctor registers good clean connections both in and out.  It has to be a yosemite security bug... talk about frustrating!

It worked perfectly before upgrade.  What I have noticed is outgoing mail DOES leave the building but only on shutting mail down and restarting, but anything created once open... nothing!  I'm not relishing the idea of manually restarting every 20 secs!!!!  Any ideas?  Will get some screenies together.

I tried all the suggestions in this thread but nothing seemed to work until I restarted my MacBook then everything worked - both send and receive burt into action and now my Mail seems to be OK.

Unfortunately, I can't be sure which fix did the trick but to all those posting here I say a really big thanks for your time and advice and would just like to add;

Once you have made any of the changes listed here, if it still doesn't seem to work - Restart your machine before trying the next fix, it may just save you some time ;o)

There are quite a few different fixes listed in this thread for this problem.

I tried all the suggestions but nothing seemed to work until I restarted my MacBook then everything worked - both send and receive burt into action and now my Mail seems to be OK.

Unfortunately, I can't be sure which fix did the trick but to all those posting here I say a really big thanks for your time and advice and would just like to add;

Once you have made any of the changes listed here, if it still doesn't seem to work - Restart your machine before trying the next fix, it may just save you some time ;o)

OMG - you just probably saved me 2 years!! [maybe in stress terms and shortened life]

Thank you TJ.  It still 'feels' a bit flakey but seems to be squirting the msgs out the door eventually.  Hope Apple crew put some hours into this one for all our sakes.

You're a genius! Thank you SO much.

Re mail not working in Yosemite... Reseting Keychain logins PLUS rebuilding the mail accounts worked great. All is well

Nothing is working for me.  I have tried all the solutions.  The weird thing is this started happening days after I upgraded to Yosemite.  Mail (incoming and outing) was working fine for both my accounts and now neither account can send emails.  To make matters worse. I now can't send or receive with hotmail.  It says my password is wrong, but I know it's correct.

So very frustrating Apple.  You need to fix this immediately.

After rebooting several times it seems to be working. I have no idea which fix worked.  I hope this stays fixed.

Check that. Yesterday all was well after resetting keychain and rebuilding the accounts. Today, it's back to no connection for my ATT UVerse imap accounts. iCloud seems to work just fine. Stumped.

Mail not working after Yosemite upgrade. Tried all things on this forum list and many articles. What I also did is go to an Apple Store and the Genius Bar folks could not figure the problem out either. However, they did create a test user account, then set up[ my email with all the previous folders,.... and my email works fine in this test account but not my named account. Genius folks think it is linked to my user account. Help Identity crisis here!

I have the same problem and cannot send SMTP mail after upgrading to Yosemite I am using my MacBook professionally and are desperate for a solution. Apple please do something about this serious bug !!!!

I had the same thing when I first updated. Just deleted the Account and set it up again. All good since and no loss of data.

Pete