Fun fact I wasn’t aware of, but learnt today thanks to a colleague.
Say you have an on-prem account with Exchange mailbox. It has a LegacyExchangeDN
attribute. When you do an MRS migration of it to Exchange Online this LegacyExchangeDN
attribute changes.
Before:
/o=xxx/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Recipients/cn=aaa-bbb ccc
After:
/o=xxx/ou=External (FYDIBOHF25SPDLT)/cn=Recipients/cn=ddd
Important to know this in case you are also moving the account across forests at the same time (coz… why not!). Must take care to capture this new LegacyExchangeDN
to the new account as a proxyAddress
.