Mac mail not sending Gmail email

Infrequently my Mac mail would be rendered incapable of sending email.

It appears the Mac mail client could not connect to the outgoing Gmail SMTP server,, then after a few hours the connection would be restored automatically.

I assumed that my settings must be fine as they remained constant, it must be a problem on the Gmail servers end, but it was happening too often for that to be plausible.

So I used the connection doctor to see what was happening under the hood.

To access the connection doctor, go to the Windows->Connection Doctor option in your Mac mail menu.

First thing I noticed was that I was trying to connect to a bunch of different outgoing servers. This is because I had set up separate email accounts (another Gmail and Yahoo mail account). It couldn’t connect to any of them, which was suspicious in itself.

Slash and burn time. I edited my SMTP servers list and I removed the 2 other outgoing servers that I never used, leaving me the one server that I always tried to use.

I ran the connection doctor again and watched the output window.

Failed to connect again, bummer. But I noticed it was using port 25 when trying to connect. That’s not right I thought, it should use port 465 if it’s using SSL. Gmail expects you to use SSL, when connecting and to use port 465.

So I edited the remaining outgoing server connection settings by doing the following.

  • Went back to editing SMTP list (described above)
  • Clicked on remaining server
  • Clicked on Advanced Tab

Instead of choosing ‘Use default posts‘, I specified a custom port 465 and made sure the ‘Use Secure Sockets Layer (SSL)‘ checkbox was checked.

Saved settings.

edit advanced outgoing server settings

Returned to connection doctor. This time I again failed to connect (boo!) but I got a different error (yay!). Authentication failed. Huh? I didn’t change anything, how did that happen… hmm.

Now I returned to edit the remaining outgoing server. Made sure the Password option was set and I re-entered my account username & password.

Saved settings again.

At this point, I was a little exasperated so I also tried unlocking my Gmail account. I was aware that Gmail lock accounts if they detect unusual behavior, so I made sure my Gmail account was unlocked by going to

Tried the connection doctor again and sweet baby zeus it connected.

Unfortunately, I cannot say for certain what was the issue. I had tried unlocking the account before I started this and it didn’t connect, so it wasn’t just that.

Anyway, thought I’d post what I tried, might help someone… might also waste 10 minutes of some punter’s life!

9 thoughts on “Mac mail not sending Gmail email

  1. Had the exact same problem and wanted to tear my hair out! This worked for me though! Thanks!

  2. Yay! Thank you so much for this post! I had a ton of messages stuck in my outgoing folder, and I’m pretty sure you just saved my email life today. 🙂

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