FYI, found the solution.

It seems doveadm can't cope with brackets in mailbox names.

I moved the user's mails into non-braketed, deleted the bracketed and doveadm backup worked fine after that.

‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐ On Sunday, 24 May 2020 14:32, Laura Smith n5d9xq3ti233xiyif2vp@protonmail.ch wrote:

Hi All,

So close and yet so far.  ;-( Have been migrating users from an old Dovecot server to a new one. All of the users have doveadm backup'd perfectly, except for one !

What does the below mean ?

$ sudo doveadm -v -o imapc_user=jd@example.org.tld -o imapc_password=secretSquirrel -o imapc_host=old-server.example.com backup -1 -R -u jd@example.org.tld imapc: dsync(jd@example.org.tld): Info: imapc(old-server.example.com:993): Connected to 10.10.10.10:993 (local 10.10.10.11:35858) dsync(jd@example.org.tld): Error: Failed to access mailbox Sent Messages (jasmin@example: Mailbox doesn't exist: Sent Messages (jasmin@example (0.001 + 0.000 secs). dsync(jd@example.org.tld): Error: Failed to access mailbox Sent Messages (jasmin@example.org: Mailbox doesn't exist: Sent Messages (jasmin@example.org (0.001 + 0.000 secs). dsync(jd@example.org.tld): Error: Failed to access mailbox Drafts (jasmin@example: Mailbox doesn't exist: Drafts (jasmin@example (0.001 + 0.000 secs). dsync(jd@example.org.tld): Error: Failed to access mailbox Drafts (jasmin@example.org: Mailbox doesn't exist: Drafts (jasmin@example.org (0.001 + 0.000 secs). dsync(jd@example.org.tld): Error: Failed to access mailbox Deleted Messages (jasmin@example: Mailbox doesn't exist: Deleted Messages (jasmin@example (0.001 + 0.000 secs). dsync(jd@example.org.tld): Error: Failed to access mailbox Deleted Messages (jasmin@example.org: Mailbox doesn't exist: Deleted Messages (jasmin@example.org (0.001 + 0.000 secs).