[Evolution] Mail is not removed from Unix spool file

[Alex S Moore <asmoore edge net>]

Using Evolution 1.4.5 with a 'Standard Unix mbox spool or directory'.  Mail
is not being removed from the file.  I do not see an option to
uncheck/check, as mentioned in the post 'POP mail not being removed'.

I was using 1.4.4 and never had this problem.  1.4.5 is a recent 'upgrade'.
 I cannot get back to the older version.

Thanks, Alex