I use IMAP gmail from opera M2.
Right now, I cannot access my mail, it says 'Invalid credentials'.
So I try to go to the actual page. It opens just fine with the same username and password. But then, any action like going back to inbox gets an 'still working' message for ... minutes.
Second, using free software (gmail, Opera) has one big downside: where do you go for support? You can of course post in forums, but if your issue is unresolved (nobody knows the solution) you are on your own.
Back in the day, I paid for opera and got support by mail. Nowadays the situation is a lot worse. It's forums post, and pray.
Same for gmail: where do I go for support? They just redirect you to their help files.
My browser and mail are critical for me. I cannot afford to be without good support. And I'm not even a business: I can imagine how stressing it can be for corporations.
Although, now that I think of it I have 1st hand experience with two large universities in the UK with mail down for weeks (Warwick and Surrey, if you must know). That is totally unthinkable. This is what made me move to gmail even though I always have an alternative provider (employer).
All in all, this is a sorry state. Suggestions?