Hi
I just tried to run the convert plugin as described at http://wiki.dovecot.org/Plugins/Convert
(except with mail_location = maildir:~/Mail)
It fails with an error message: Eopen(/.temp.falcon.endbracket.net.18618.8d5e0a038da6cf06) failed: Permission denied Error: imap dump-capability process returned 89
It looks like Dovecot execs /usr/libexec/dovecot/imap, which drops root privileges (probably via get_imap_capability), then loads /usr/lib/dovecot/imap/lib01_convert_plugin.so, which tries to create a file in the root directory, which it obviously won't have write privileges on.
I'm running dovecot-1.0-1.2.rc15.el5 on CentOS 5.
If I change the paths from ~ to /home/%u, I get this error message: Emkdir_parents(/home/dump-capability/mail) failed: Permission denied