Mail account offline
Hi,
My mail account has gone offline on my iMac. The little lightning bolt symbol has appeared saying mail account offline. If I click it, it won't let me sign in. The error message is below.
I've tried Mail>Take accounts online, which didn't work. I've tried deleting the Gmail account and re-adding it from scratch, but when I try to add it again, I get the same message. This is exactly the same account that I use on my iPad and iPhone and there has been no problem with either of those devices.
My Mac runs High Sierra - if that helps.
Thanks in advance for any help.
iMac 21.5″, macOS 10.13