Hi Jay
Perhaps our observations will help.
We're currently evaluating an MS Exchange alternative. Smartermail is promising, but we're still experiencing some major Outlook/Windows authentication issues with LDAP.
1. Password prompt once per MAPI connection (multiple connections possible. Examples: public folders, shared mailboxes...). "Remember my credentials" is required.
-> Outlook/Exchange is able to pass through credentials.
2. New AD user: password prompt -> Requires webmail login first.
3. AD user password change: Password prompt -> Requires webmail login first.
-> Imagine 200 Outlook users, password change twice a year = 400 support tickets.
We're in contact with Smartermail support to solve these issues. Fortunately, the support team is very friendly and responsive.
Update 1: According to SmarterMail support, this is normal behavior. There are plans to implement OAuth, but without a release date.
At this point in time, this is not a viable alternative to MS Exchange.