Ask the support at that web site what's up. Just yesterday I had login troubles and the site had changed and special steps were needed. Their fix may not apply to your certain school email account.
Windows 10. When I log onto a certain school email account, from any browser, and put in my username and password, it says 'invalid'. Yet on a smartphone it works as usual! The email site says nothing changed with them, and all other email usernames and passwords work ok on all other sites. It's as if the site isn't registering my info, but only from my computer, and again, this happens from any browser. Any suggestions?

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic