I'm migrating a mailbox from dovecot v2.2 to v2.4. Not that it
matters, I'm also changing from mbox to Maildir.

As an initial test I used this command:

sudo doveadm sync -1D -u theuser -m amailbox remote:theuser@destination.com

I received this error: Error: doveadm: Unexpected or incomplete option: -U

After changing the dsync_remote_cmd to:

dsync_remote_cmd = ssh -l%{login} %{host} doveadm dsync-server -u%u

I was able to transfer the mailbox without issue.

Before changing it, the setting on the source server was:

dsync_remote_cmd = ssh -l%{login} %{host} doveadm dsync-server -u%u -U

I'm interested to discover what the -U was intended for since I
couldn't find specific documentation to its use.

I'll accept that it was a legacy thing and removing it won't cause any
unintended consequences...but I do still have that curiosity about
what it was for.

Additionally, the subscription status doesn't seem to flow to the new
server. When checking the source server with:

doveconf -d | grep subscriptions doveconf -n | grep subscriptions

No value is returned...So I'm wondering if I need to specifically set
subscriptions = yes in the source server to make this happen properly.

Maybe this is an artifact of using sync -1?

Thanks for any insight you may provide.

Mike