Q: gmail imap won't connect with Apple Mail 4.6

Troubleshooting Apple Mail

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

Mail not sending or receiving messages after updating OS X

Did that help you?  I am using Mail 4.6 (1085)  and I cannot connect when I make a new email account.  My old accounts work fine.  I got a message in the Gmail account (via browser) that an insecure app had tried to access my account.

I was able to connect through Thunderbird.  When I set that up, it opened up a window to Gmail where I authorized Thunderbird to access my email.  I have no such option when I try through Mac Mail.

I had no problems on iOS connecting without any special authorization.  I have the SSL option checked.

Try looking/posting here.

Gmail Support

https://support.google.com/mail/troubleshooter/1668960?authuser=2&hl=en&rd=1

This is a more specific  help listing.  I already went through that.  The funny thing is, Google says if that does not work, to contact Apple.  LOL.

That is why I am here.

As far as I can tell, I have all the accounts setup the same.  But the new one will not connect.  Apparently Google now thinks that Apple Mail 4.6 (1085) is an unsecure client.  Yet I can connect with the same settings in Thunderbird and iOS.

Perhaps those who have upgraded to the most recent Mac OS are not having this issue.  But I cannot upgrade due to incompatible software that I need to run and cannot replace.

Did you look at the troubleshooting links I posted earlier? What does Connection Doctor show?

It tells me nothing that I find particularly useful.  It goes through a series of bars that flash on and off quickly, then disappear.

In my list of Inboxes, my three older Gmail accounts are darkened (normal) and active.  The two newer accounts that I have recently setup stay gray in lettering and are inactive.

When I select "Take All Accounts Online", they momentarily go dark, then go gray again.  When I do that, the activity window flashes up several bars, then clears.

I do not get any errors when doing this in the Activity Window.

If I delete the account and re-enter it, Apple Mail tells me that it cannot connect to Gmail (or some similar wording).

Yet when I set it up exactly the same way in Thunderbird and iOS, I can IMAP my mail just fine.  So the problem is not in the settings in Gmail.  It must either be a setting that I have missed in Apple Mail (I have compared working and non-working accounts and find no difference), or that Gmail will not accept my older Apple Mail app.

Did  you notice my comment that Gmail notified me that my account was contacted by an unsecure App the first time I tried to connect with Apple Mail?

Could that be the issue?

Did you also notice that when I successfully connected with Thunderbird, that a window opened up in Thunderbird that looked like a browser window, that took me to Gmail and asked if I wanted to authorize Thunderbird to access my account?  Nothing like that has ever happened with Apple Mail.

This is the type of message I get from Google when I try to sign in with Apple Mail. 

I found my answer.  There is a place in Google to allow access by less secure Apps.  My Apple Mail must be old enough to be less secure.

https://www.google.com/settings/u/0/security/lesssecureapps