Still can't send email with Yosemite due to SMTP offline?

I deleted the accounts and tried to re-add them. Now, the Google account will load everything EXCEPT mail.

Mail troubleshooting - Yosemite

What does Mail/Window/Connection Doctor Show? If the server is red, select it and look at the Show Details box.

Troubleshooting sending and receiving email messages

Troubleshooting sending email messages

I had the same problem - it kept saying my outgoing mail server was 'Offline' and nothing tried was working. I even removed the account completely and attempted to reinstall.

I then realized it was because I had the two-step security verification on my Gmail account. If you do, too, you have to also enter the two-step verification code to the OUTGOING mail server when you set up your mailbox on your Mac.

To do this, go your Mail>Preferences, then look at the Outgoing Mail Server (SMTP) field. It will probably say "Offline". Click in the dropdown box and select 'Edit SMTP Server List'.

You'll then see a 'Password' box. Enter the 2-step verification code that was generated by Gmail, and you should be good to go!

Well this is not the answer.

I also disabled the 2-step verification and reenter the SMTP parameters.

At first time it seemed to work (I could send emails), but after having quit and restart Mail I still got the error "Offline".

My only solution is to kill the SMTP parameter and to recreate it (smtp.gmail.com, SSL, login + pwd, etc.). And that for each mail to be sent ! 😟 😟 😟

I found a solution, which in my case, helps greatly in Yosemite to keep Mac Mail online, and if it does go offline, makes it much easier to reconnect. In Mail's menu bar, click Mail / Accounts. It is the same as to System Preferences / Internet Accounts. (Not to be confused with Mail / Preferences / Accounts).

In Internet Accounts, click on each mail account. If "Use With" has "Notes" checked, or anything else which does not need to coordinate with Mail, uncheck it. I'm not sure why, but every one of my Mail accounts had "Notes" checked, but without the mail log-ins entered, such as passwords. I don't need Notes to coordinate with Mail in any way (I'm not even sure what the function is for).

When you uncheck "Notes" or perhaps another use, in the list of accounts, you'll then see a greyed-out, inactive account with the same name as your active account (in my case, the greyed-out duplicate accounts were called "Mail & Notes Account" when clicking on them.) Try using Mail now for a week or so. If it's much better, then eventually just delete the inactive accounts in Mail / Accounts (or in System Preferences / Internet Accounts, which is the same settings). I hope it works for others! 🙂