Is it possible to use a variable as the delimiter using basename?

I have a num variable that will be changing in the filename now.
The files could looke like this

my.email.address@mydomain.com.VL010600_474
my.email.address@mydomain.com.VL020600_474
my.email.address@mydomain.com.VL030600_474
my.email.address@mydomain.com.VL040600_474

I'm tryin to loop thru and use a variable for the delimiter.

delim=".VL0$num0600_474"
email=`basename $f $delim`
echo "email = $email " >> /home/myname/xls.logfile

When I look at the email variable, it has the delimiter tacked on to it instead of just the email address.

I really appreciate all the suggestions.