Dealing with email issues in macOS can be a tricky thing. And is not always straightforward – Is the issue with the account? Your server or with macOS Mail.
Here are some tips and methods to find out what may be going on. How to interpret certain error states and error messages. I’ll recommend common settings and warn of cave-ats. And how to fix stuff in macOS mail.
If your mail is not working
Your first step is to restart the macOS mail client. See if it works then. If not. Go to the Window Menu and click “Connection Doctor”.
A new window should open, checking all your settings.
Interpreting the error
Connection doctor lists all your email accounts 2 times, one for incoming and one for outgoing email. In the above example I deliberately broke one account – It’s marked with a red dot and the exact error is displayed behind it.
This means I have to check my settings, check the username and password. In my scenario the password is missing. When I add it in settings and check again everything shows green.
Of-course once we know what’s wrong with the email settings. I can go into settings and correct what macOS Mail thinks is wrong with it. In my case something with the username and password.
Things to check
View the screenshots here – And especially the items marked with a red arrow which are essential for a working mail account. Reach these menus via the Mail > Preferences menu.
Common Email ports:
Secure IMAP – port 993
Secure POP3 – port 995
Secure SMTP – port 465
Standard IMAP – port 143
Standard POP3 – port 110
Standard SMTP – port 25 / 587
Disable automatic settings detection
There are 2 easy checkboxes to disable this silly behaviour and give some freedom over what macOS Mail does.
In Mail Preferences, under each account in Advanced there is this little checkbox.
And in SMTP Server List for each server in Advanced is this similar checkbox.
Uncheck both and set your settings as you need. Save and restart the macOS Mail client.
Why? Since Apple knows just about *nothing* about your hosting providers servers it can’t possibly guess the right settings with any accuracy. Some hosting providers have a autodiscovery feature that may work. But in my experience Apple can’t seem to interpret that too well.
IMAP vs. POP3
If you receive your email on multiple devices you should try to use IMAP. This means that your email is synced via the mail server to all your devices. POP3 can not do that and will download emails on the device that asks for them first. Leaving the other devices without those emails. Having an asynchronous email setup like that is very 1995 and not very efficient. Most providers support IMAP these days. If you can, ditch POP3.
Security and privacy concern
If you can, always use the secure option. Check with your email provider if this is possible! When using a secure connection your email is encrypted end-to-end so nobody can snoop around and you can feel more comfortable sending eyes-only information.
Saving the settings
Saving the settings is done by either moving to another tab (top), selecting another account (left sidebar) or closing the settings window completely and confirming at the prompt.
Note: This post applies to pretty much every recent version of Mac OS X and macOS. So Tiger, Leopard, Snow Leopard, Lion, Mountain Lion, Mavericks, Yosemite and Sierra *all* have this tool. Probably older versions too.