dovecot log shows: service=imap ... Error: Temp file creation to /tmp/dovecot.imap. failed: No such directory

[Peter Kielbasiewicz]

I am using dovecot 2.2 with plesk 12 and I have made no modifications to the dovecot config.
Logwatch reports the messages below.
The errors don't seem to appear for every imap connect as can be seen from the number of deliveries and successful logins.
So what makes dovecot fail sometimes to create the /tmp/dovecot.imap?


Dovecot Deliveries: 19
 Dovecot IMAP and POP3 Successful Logins: 106
 Dovecot disconnects: 72

 **Unmatched Entries**
    dovecot: message repeated 4 times: [ service=imap, user=tester at example.com, ip=[::1]. Error: Temp file creation to /tmp/dovecot.imap. failed: No such file or directory]: 1 Time(s)
    dovecot: message repeated 5 times: [ service=imap, user=tester at example.com, ip=[::1]. Error: Temp file creation to /tmp/dovecot.imap. failed: No such file or directory]: 1 Time(s)
    dovecot: service=imap, user=tester at example.com, ip=[::1]. Error: Temp file creation to /tmp/dovecot.imap. failed: No such file or directory: 10 Time(s)
    dovecot: service=imap, user=tester at example.com, ip=[::1]. Error: Temp file creation to /tmp/dovecot.imap. failed: No such file or directory: 1 Time(s)