chroot: Error: Temp file creation to /tmp

[bvr]

Hello,

We are using dovecot (2.2.10) and it's working great! When I enable 
chrooting by appending /./ to the homedirs I'm getting errors like this:

mail1 dovecot[47074]: imap(user): Error: Temp file creation to 
/tmp/dovecot.imap.mail1.70079. failed: No such file or directory

On the surface everything seems to be working fine and I have not been 
able to produce the error myself.

Any ideas?

Thanks in advance,
bvr.