On echoserver the import appended 23,045 messages one by one over a single
IMAP session, about six per second, and the deploy waited 62 minutes for
it inside the Keycloak stage, because Stalwart is a dependency of Keycloak.
galaxyserver holds 157,655 messages in one mailbox, which one session
would need 7 to 28 hours for, beyond the task's six-hour timeout.
migrate_from_mailu.py now opens several IMAP sessions per mailbox that
take messages from one queue in file name order, with the dedup set and
the counters under a lock, and logs [PROGRESS] every 1000 messages. A
session Stalwart refuses only lowers the parallelism; with one session
the import behaves exactly as before. The number of sessions is
services.stalwart.migration.workers, or one fewer than the host's vCPUs,
at least 1 and at most 8.
The deploy starts the import as the transient unit stalwart-mailu-import
and does not wait for it; a deploy that finds the unit running leaves it
alone. The unit removes the staged recovery administrator credentials when
it stops, and a failed start removes them in a justified rescue before it
re-raises. Progress and the closing [DONE] rc=<n> are in
journalctl -u stalwart-mailu-import.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
kevinveenbirkenbachandClaude Opus 5.5
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