If you're thrown an Unknown MAPI Error: MAPI_E_NOT_FOUND when logging with a newly created account on Kopano, it is mostly because the user does not have a store. The kopano-server log doesn't help much to identify this neither does the webapp which only throws the MAPI error.

It is most likely to occur when using an external user database such as LDAP. The users database is synced successfully with LDAP, creating the new user but the store is not created and attached to the account.

In the case if the user was not synced the kopano-server log would have a proper message indicating that it failed to authenticate using the LDAP plugin.

Jan 25 18:26:35 kopano-1 kopano-server[28463]: Authentication by plugin failed for user "bajirao.singham": Trying to authenticate failed: Failure connecting any of the LDAP servers; username = bajirao.singham

If the user could not authenticate then the webapp would display a "logon failure" message while asking to verify credentials. It would not display the MAPI error.

Checking the user details with kopano-admin does however hint at the missing store.

$ kopano-admin --details bajirao.singham
User object id:         00000000AC21A95040D3EE48B319FBA75330442501006001
WARNING: Unable to get user store entry id. User possibly has no store.

User store id:          
Username:               bajirao.singham
Fullname:               Bajirao Singham
Emailaddress:           bajirao.singham@xxx.xxxxxx.xxx
Active:                 yes
Administrator:          no
Address book:           Visible
Auto-accept meeting req:no
Mapped properties:
        0x8C6D0102                      48 bytes
        PR_GIVEN_NAME                   Bajirao
        PR_BUSINESS_TELEPHONE_NUMBER    +2301234567
        0x3A0C001E                      en_US
        PR_SURNAME                      Singham
        PR_TITLE                        Police Officer
        PR_MOBILE_TELEPHONE_NUMBER      +23051234567
        PR_LOCALITY                     Shivgarh
        PR_POSTAL_CODE                  457001
        PR_EC_ENABLED_FEATURES          mobile; outlook; webapp
        PR_EC_DISABLED_FEATURES         imap; pop3
Unable to show object quota information: missing or invalid argument (0x80070057)
Groups (1):
        Police Force

Create a store using the kopano-admin tool.

$ kopano-admin --create-store bajirao.singham

The store will be created and hooked to the bajirao.singham user account in the above example. Login with the account should then be successful.