Office 365 sign in prompt when setting up Exchange email account on iPad, iPhone or Mac Mail
The issue arrives when you are attempting to configure a new exchange account that is not hosted on office 365 but you keep getting a prompt to sign into office 365 mail account when you attempt to add a new account for a domain.
The can be very confusing as if you have host your own services, or have a host that knows what they are doing, you can have an exchange email account that is not part of office 356 but yet you will see the prompt for sign into office 365 when attempting to set up the account on apple devices. It could well be that it also prompts with non apple devices, we did not bother to test.
The issue likely arises from the situation where office 365 services were once associated with the email domain in question. Commonly services like Godaddy will allow it’s users to simply click a few buttons and sell office 365 email services. If a user has previously had an office 365 email service, then this needs to be removed from the service that originally set this up.
We have done extensive checking with DNS and Autodiscover settings and found that even when DNS correctly has the new discovery settings of the own premises Exchange server, or third party Exchange comparable email service (SmarterMail etc) that it will still fail to find the server for login, but will offer previously activated office 365 services for login.
Apple products appear to do a check on office 365 for the domain, and if they find a provisioned service, they will offer that login without a way to skip.
The only way we found to solve this is to unsubscribe and remove the provision of any and all email accounts on that domain name in question. In Godaddy it was a matter of removing the configured email accounts. This took about 15 minutes to complete and remove domain associated records from the office 365 service. Once complete a signing was accepted as expected.