Looks like are we have similar issues with our SmarterMail system:
We are receiving the System-Messages with Delivery-Notification for all outgoing emails, but only for the automatically by our SmarterMail/Events automatically added "journal@"-recipient/account used for our message-archiving software.
Our Events "Journal Incoming" and "Journal Outgoing" - both just do "Add recipient" firstname.lastname@example.org
and under "Spool" and "Waiting for Delivery" are many, many hundreds/thousounds of emails.... most of them dealing with delivering to our local journal-useraccount (looks like only this "last/added recipient" ist failing, originally recipients are already ok/success!
Could even be that some kind of messages having "looping issues" because often many, many, many textlines with "Failed" :-(I can even see "mailbox is locked" messages in the delivery log for the journal-account, re-indexing was no solution, still seeing this issues/SystemMessages with delivery failure
[2019.08.14] 17:20:46.631  Add message to mailbox call failed. Reason: Access to the grp file is locked, monitor enter failed.
[2019.08.14] 17:20:46.631  Delivery attempt to email@example.com to folder 'Inbox' failed. Mailbox is locked.I tried with SystemMessages and "empty from address", and even with entering "postmaster as the from-address", this did not make any difference concerning the messages/failure-emails.
And our users do think, that there original/destination was not working, they do not notice that in our case it is just our "journal"-recipient failing!tested with v17 / build 7153 and even with the MAPI-beta 7159
looks like the bug/issue is not solved/fixed yet.