Checking TA: SMTP: followed by Error 0xe1000005. Internal DSA error (4259903)

Synchronization properties show many failed objects with "Internal DSA Error"

In dsa.log the "Error 0xe1000005. Internal DSA error" is preceeded by "Checking TA: SMTP:" similar to the following:

11/17/17 13:00:14 (GMT-00:00)     Common AcAdSwitches     Searching target conflicts in pack...
11/17/17 13:00:14 (GMT-00:00)     Common AcAdSwitches         Checking TA: SMTP:
11/17/17 13:00:14 (GMT-00:00)     Common AcAdSwitches Error 0xe1000005. Internal DSA error
11/17/17 13:00:14 (GMT-00:00) Activation AcAdSwitches     Mail Switch, "Apply" method done

Locate the problem objects by running the following LDAP query against the source domain:

(&(mailNickname=*)(!(LegacyExchangeDN)))

Use one of the following appoarches to resolve the issue:

- exclude problem objects from sync

- clear mailnickname from problem objects

- populate LegacyExchangeDN on problem objects