dsync: Add per-mailbox sync lock that is always used. Both importing and exporting gets the lock before they even sync the mailbox. The lock is kept until the import/export finishes. This guarantees that no matter how dsync is run, two dsyncs can't be working on the same mailbox at the same time. This lock is in addition to the optional per-user lock enabled by the -l parameter. If the -l parameter is used, the same lock timeout is used for the per-mailbox lock. Otherwise 30s timeout is used. This should help to avoid email duplication when replication is enabled for public namespaces, and maybe in some other rare situations as well.

#ifndef POP3_PROXY_H
#define POP3_PROXY_H

void pop3_proxy_reset(struct client *client);
int pop3_proxy_parse_line(struct client *client, const char *line);

void pop3_proxy_error(struct client *client, const char *text);
const char *pop3_proxy_get_state(struct client *client);

#endif