Office365 error: Invalid server response. HTTP/1.1 403 Forbidden

[Gimano]

server name: outlook.office365.com
Security: SSL strict check port 443
login: login@domain (=email address)

The same configuration works with the stock mail client.

What can I do?

[Kostya Vasilyev]

Yes, the server for Office 365 should be outlook.office365.com

Please double check -- I've got an Office 365 account working with these settings just fine (and been for years).

Oh, and you will want to choose "Exchange" account type, not "Internet Mail" (while adding the account into AquaMail).

[Gimano]

I configured it just like that but it won't work.

Let me give some background information.
First I tried with Aquamail, didn't work, same issue as I have now.
Then I added the account through android settings - accounts. That worked and the account was created for the stock mail client.
I received one mail only, the mail tells me to register the device on a portal site (it's a company mail account and we have some extra security).
All mails came in after I registered the device.
I tried again on aquamail and it's still the same issue.

Does the login require a slash/backslash in front of the "login@domain"?
Anything else? I'd very much prefer have all my mail accounts in the same client.

[Kostya Vasilyev]

Ah.

Your corporate IT people must have disabled access via EWS (Exchange Web Services, the network protocol used by AquaMail and few other mail apps) -- and only left ActiveSync enabled.

Something to be aware of is -- even if we somehow got AquaMail to work, if your IT department ever found out, they wouldn't be happy.

[Gimano]

Yes that makes sense. There is an extra security layer with challenge pass codes for browser access and approved devices for mobile devices, so I wouldn't be surprised if they left out some connection options as well. OK so the stock app doesn't use EWS? And Aquamail can't use ActiveSync?

Not sure if I agree with your statement, if you make something work by simply using it then you're allowed to do it ;-)
But I'm not trying anything hardcore here, I prefer to have everything on aquamail but if it just won't work then bad luck for me.

[Kostya Vasilyev]

Re: OK so the stock app doesn't use EWS? And Aquamail can't use ActiveSync?

"stock" Email app uses ActiveSync

Gmail app uses ActiveSync.

I don't (the forum has several excessively long discussions about the reason).