OK, I see where I mis-diagnosed the problem.  It seems that importing
smtplib (for example) shouldn't get confused with my email package.  As
I understand it, using relative imports within a package should avoid
the problem of the names of subordinate packages/modules colliding with
those in other packages.  Should the problem have been written up that
the standard modules (e.g., smtplib) should use relative imports to
avoid name collision problems like this?  (I'm not sure if relative
imports work for standard modules).

If this is the correct statement of the problem, I can resubmit it if
that's easier.

Thanks in advance!