Everytime I try to login into my email account on my iMac it says my password is not valid, and I'm offline. Previously worked fine - what happened? If I go to google it works fine!

Hello, davenrich.

•What type of email account has the problem? Gmail? AOL?

We can help you best if you will please tell us a bit more about your Mac.

Which model and model year is the computer and what macOS version are you running?

If you are able, click the Apple () menu > About This Mac.  There you will find the specifics we can use to help you best.

(Note- for privacy and security please do not post your serial number.)