All of a sudden I am getting this error message when trying to receive emails. I haven't changed any settings, icloud mail is on in system preferences and I've followed the help I've found on here, but to no avail.
It's been intermittently going on for around a week now and it's stopping me from being able to do my job.
Try toggling Mail off and then back on to see if that will jumpstart Mail.
Also give this a try: boot into Safe Mode according to How to use safe mode on your Mac and test to see if the problem persists. Reboot normally and test again.
NOTE 1: Safe Mode boot can take up to 3 - 5 minutes as it's doing the following;
• Verifies your startup disk and attempts to repair directory issues, if needed
• Loads only required kernel extensions (prevents 3rd party kernel/extensions from loading)
• Prevents Startup Items and Login Items from opening automatically
• Disables user-installed fonts
• Deletes font caches, kernel cache, and other system cache files
NOTE 2: if you have a wireless keyboard with rechargeable batteries connect it with its charging cable before booting into Safe Mode. This makes it act as a wired keyboard as will insure a successful boot into Safe Mode.
Mail unable to open mailbox on iphone/imac/macbook and online
