[Dovecot] backup using rsync

[Scott Murman]

i'm trying to backup the dovecot Maildir files over a cifs share.    
source is a debian build, share is a readynas.   i've been getting  
rsync: mkstemp 'filename goes here' failed: Not a directory (20)  
errors.   rsync is v3.0.   i believe this is related to the dovecot  
file naming convention that includes characters such as ':' in the  
filename.   anyone else seeing similar behavior?  a workaround?   i  
can go to different backup strategies, but rsync is cheap and  
effective for my needs.  thanks,

-SM-