When setting up an email account in a client using autodiscover, a certain set of information is expected in the response from the mail server. SmarterMail sends back the required information, regardless of the protocol being used. How email clients handle that information, however, is based on the email client.
While every effort is made to ensure all clients will process the autodiscover information correctly, changes to clients can break autodiscover functionality. This is especially true with Microsoft Outlook. Microsoft continually changes their email client to conform to the changes they make to their own services. For example, setting up an Exchange account in Outlook continues to be problematic, unless you're using Office 365. (There was a point in time where you had to make registry changes in order to add a non-Office 365 Exchange account.)
As a result of our testing, autodiscover works in some versions of Outlook, but not others. In addition, while it may work with one protocol, it may not work when using another. (IMAP versus MAPI, for example.) Oddly enough, autodiscover works fine in clients such as eM Client and even Windows Mail. Outlook is the outlier.
Moving forward, we will not be making changes to how SmarterMail's autodiscover feature works with Outlook except in cases where legacy protocols such as IMAP and POP are concerned. Our support of EAS for Outlook for Windows is ending, just as Microsoft's own support for EAS and Outlook for Windows has already ended. (It is still THE ideal protocol for mobile synchronization, however.) During a meeting with Microsoft protocol experts, our developers were told that while EAS "may" work for Outlook on the desktop, it was really never intended to work and they are no longer supporting EAS for Outlook integration.
Instead, system administrators looking to provide Outlook users with a true synchronization experience will want to use MAPI.