DTS-Package Sends Mail And Files Before The Job Finishes

I have a package which truncates files, fills them with data and
should send a mail with the files as attachment when it finishes
running. In between, when the task is still running mail is sent with
empty files. When I take a look at the directory (at the end of the
task), where the files are created I find out that the files are not
empty.

(e.g. in task: doA->doB->doC->SendMail. But instead of waiting till
doB->doC finishes, it does the following: doA->SendMail ... may be
because doB takes long.)

Can I indicate anywhere that it should delay the mail until at the end
of the task?

Thanks in advance.
Harp